table of contents
other versions
- jessie-backports 0.6.5.9-5~bpo8+1
- stretch 0.6.5.9-5
- testing 0.7.12-2
- stretch-backports 0.7.12-1~bpo9+1
- unstable 0.7.13-1
zfs(8) | System Administration Commands | zfs(8) |
NAME¶
zfs - configures ZFS file systemsSYNOPSIS¶
zfs [-?]
zfs create [-p] [-o property=value] ... filesystem
zfs create [-ps] [-b blocksize] [-o property=value] ... -V size volume
zfs destroy [-fnpRrv] filesystem|volume
zfs destroy [-dnpRrv] filesystem|volume@snap[%snap][,...]
zfs destroy filesystem|volume#bookmark
zfs snapshot | snap [-r] [-o property=value] ... filesystem@snapname|volume@snapname ...
zfs rollback [-rRf] snapshot
zfs clone [-p] [-o property=value] ... snapshot filesystem|volume
zfs promote clone-filesystem
zfs rename [-f] filesystem|volume|snapshot filesystem|volume|snapshot
zfs rename [-fp] filesystem|volume filesystem|volume
zfs rename -r snapshot snapshot
zfs list [-r|-d depth][-Hp][-o property[,property]...] [-t type[,type]..] [ -s property] ... [-S property] ... [filesystem|volume|snapshot] ...
zfs set property=value filesystem|volume|snapshot ...
zfs get [-r|-d depth][-Hp][-o field[,...]] [-t type[,...]] [ -s source[,...]] "all" | property[,...] filesystem|volume|snapshot ...
zfs inherit [-rS] property filesystem|volume|snapshot ...
zfs upgrade [-v]
zfs upgrade [-r] [-V version] -a | filesystem
zfs userspace [-Hinp] [-o field[,...]] [-s field] ... [ -S field] ... [-t type[,...]] filesystem|snapshot
zfs groupspace [-Hinp] [-o field[,...]] [-s field] ... [ -S field] ... [-t type[,...]] filesystem|snapshot
zfs mount
zfs mount [-vO] [-o options] -a | filesystem
zfs unmount | umount [-f] -a | filesystem|mountpoint
zfs share -a | filesystem
zfs unshare -a filesystem|mountpoint
zfs bookmark snapshot bookmark
zfs send [-DnPpRveL] [-[iI] snapshot] snapshot
zfs send [-eL] [-i snapshot|bookmark] filesystem|volume|snapshot
zfs receive | recv [-vnFu] filesystem|volume|snapshot
zfs receive | recv [-vnFu] [-d|-e] filesystem
zfs allow filesystem|volume
zfs allow [-ldug] "everyone"|user|group[,...] perm|@setname[,...] filesystem|volume
zfs allow [-ld] -e perm|@setname[,...] filesystem|volume
zfs allow -c perm|@setname[,...] filesystem|volume
zfs allow -s @setname perm|@setname[,...] filesystem|volume
zfs unallow [-rldug] "everyone"|user|group[,...] [perm|@setname[,... ]] filesystem|volume
zfs unallow [-rld] -e [perm|@setname[,... ]] filesystem|volume
zfs unallow [-r] -c [perm|@setname[ ... ]] filesystem|volume
zfs unallow [-r] -s @setname [perm|@setname[,... ]] filesystem|volume
zfs hold [-r] tag snapshot...
zfs holds [-r] snapshot...
zfs release [-r] tag snapshot...
zfs diff [-FHt] snapshot snapshot|filesystem
DESCRIPTION¶
The zfs command configures ZFS datasets within a ZFS storage pool, as described in zpool(8). A dataset is identified by a unique path within the ZFS namespace. For example:pool/{filesystem,volume,snapshot}
where the maximum length of a dataset name is MAXNAMELEN (256 bytes). A dataset can be one of the following: file system
A ZFS dataset of type filesystem can be
mounted within the standard system namespace and behaves like other file
systems. While ZFS file systems are designed to be POSIX
compliant, known issues exist that prevent compliance in some cases.
Applications that depend on standards conformance might fail due to
nonstandard behavior when checking file system free space.
volume
A logical volume exported as a raw or block device. This
type of dataset should only be used under special circumstances. File systems
are typically used in most environments.
snapshot
A read-only version of a file system or volume at a given
point in time. It is specified as filesystem@name or
volume@name.
bookmark
Much like a snapshot, but without the hold on
on-disk data. It can be used as the source of a send (but not for a receive).
It is specified as filesystem#name or volume#name.
ZFS File System Hierarchy¶
A ZFS storage pool is a logical collection of devices that provide space for datasets. A storage pool is also the root of the ZFS file system hierarchy. The root of the pool can be accessed as a file system, such as mounting and unmounting, taking snapshots, and setting properties. The physical storage characteristics, however, are managed by the zpool(8) command. See zpool(8) for more information on creating and administering pools.Snapshots¶
A snapshot is a read-only copy of a file system or volume. Snapshots can be created extremely quickly, and initially consume no additional space within the pool. As data within the active dataset changes, the snapshot consumes more data than would otherwise be shared with the active dataset. Snapshots can have arbitrary names. Snapshots of volumes can be cloned or rolled back. Visibility is determined by the snapdev property of the parent volume. File system snapshots can be accessed under the .zfs/snapshot directory in the root of the file system. Snapshots are automatically mounted on demand and may be unmounted at regular intervals. The visibility of the .zfs directory can be controlled by the snapdir property.Bookmarks¶
A bookmark is like a snapshot, a read-only copy of a file system or volume. Bookmarks can be created extremely quickly, compared to snapshots, and they consume no additional space within the pool. Bookmarks can also have arbitrary names, much like snapshots. Unlike snapshots, bookmarks can not be accessed through the filesystem in any way. From a storage standpoint a bookmark just provides a way to reference when a snapshot was created as a distinct object. Bookmarks are initially tied to a snapshot, not the filesystem/volume, and they will survive if the snapshot itself is destroyed. Since they are very light weight there's little incentive to destroy them.Clones¶
A clone is a writable volume or file system whose initial contents are the same as another dataset. As with snapshots, creating a clone is nearly instantaneous, and initially consumes no additional space. Clones can only be created from a snapshot. When a snapshot is cloned, it creates an implicit dependency between the parent and child. Even though the clone is created somewhere else in the dataset hierarchy, the original snapshot cannot be destroyed as long as a clone exists. The origin property exposes this dependency, and the destroy command lists any such dependencies, if they exist. The clone parent-child dependency relationship can be reversed by using the promote subcommand. This causes the "origin" file system to become a clone of the specified file system, which makes it possible to destroy the file system that the clone was created from.Mount Points¶
Creating a ZFS file system is a simple operation, so the number of file systems per system is likely to be numerous. To cope with this, ZFS automatically manages mounting and unmounting file systems without the need to edit the /etc/fstab file. All automatically managed file systems are mounted by ZFS at boot time. By default, file systems are mounted under /path, where path is the name of the file system in the ZFS namespace. Directories are created and destroyed as needed. A file system can also have a mount point set in the mountpoint property. This directory is created as needed, and ZFS automatically mounts the file system when the zfs mount -a command is invoked (without editing /etc/fstab). The mountpoint property can be inherited, so if pool/home has a mount point of /export/stuff, then pool/home/user automatically inherits a mount point of /export/stuff/user. A file system mountpoint property of none prevents the file system from being mounted. If needed, ZFS file systems can also be managed with traditional tools (mount, umount, /etc/fstab). If a file system's mount point is set to legacy, ZFS makes no attempt to manage the file system, and the administrator is responsible for mounting and unmounting the file system.Deduplication¶
Deduplication is the process for removing redundant data at the block-level, reducing the total amount of data stored. If a file system has the dedup property enabled, duplicate data blocks are removed synchronously. The result is that only unique data is stored and common components are shared among files. WARNING: DO NOT ENABLE DEDUPLICATION UNLESS YOU NEED IT AND KNOW EXACTLY WHAT YOU ARE DOING! Deduplicating data is a very resource-intensive operation. It is generally recommended that you have at least 1.25 GB of RAM per 1 TB of storage when you enable deduplication. But calculating the exact requirenments is a somewhat complicated affair. Please see the Oracle Dedup Guide for more information.. Enabling deduplication on an improperly-designed system will result in extreme performance issues (extremely slow filesystem and snapshot deletions etc.) and can potentially lead to data loss (i.e. unimportable pool due to memory exhaustion) if your system is not built for this purpose. Deduplication affects the processing power (CPU), disks (and the controller) as well as primary (real) memory. Before creating a pool with deduplication enabled, ensure that you have planned your hardware requirements appropriately and implemented appropriate recovery practices, such as regular backups. Unless necessary, deduplication should NOT be enabled on a system. Instead, consider using compression=lz4, as a less resource-intensive alternative.Native Properties¶
Properties are divided into two types, native properties and user-defined (or "user") properties. Native properties either export internal statistics or control ZFS behavior. In addition, native properties are either editable or read-only. User properties have no effect on ZFS behavior, but you can use them to annotate datasets in a way that is meaningful in your environment. For more information about user properties, see the "User Properties" section, below. Every dataset has a set of properties that export statistics about the dataset as well as control various behaviors. Properties are inherited from the parent unless overridden by the child. Some properties apply only to certain types of datasets (file systems, volumes, or snapshots). The values of numeric properties can be specified using human-readable suffixes (for example, k, KB, M, Gb, and so forth, up to Z for zettabyte). The following are all valid (and equal) specifications:1536M, 1.5g, 1.50GB
The values of non-numeric properties are case sensitive and must be lowercase, except for mountpoint, sharenfs, and sharesmb. The following native properties consist of read-only statistics about the dataset. These properties can be neither set, nor inherited. Native properties apply to all dataset types unless otherwise noted. available
The amount of space available to the dataset and all its
children, assuming that there is no other activity in the pool. Because space
is shared within a pool, availability can be limited by any number of factors,
including physical pool size, quotas, reservations, or other datasets within
the pool.
This property can also be referred to by its shortened column name,
avail.
compressratio
For non-snapshots, the compression ratio achieved for the
used space of this dataset, expressed as a multiplier. The used
property includes descendant datasets, and, for clones, does not include the
space shared with the origin snapshot. For snapshots, the compressratio
is the same as the refcompressratio property. Compression can be turned
on by running: zfs set compression=on dataset. The default value
is off.
creation
The time this dataset was created.
clones
For snapshots, this property is a comma-separated list of
filesystems or volumes which are clones of this snapshot. The clones'
origin property is this snapshot. If the clones property is not
empty, then this snapshot can not be destroyed (even with the -r or
-f options).
defer_destroy
This property is on if the snapshot has been
marked for deferred destruction by using the zfs destroy -d
command. Otherwise, the property is off.
filesystem_count
The total number of filesystems and volumes that exist
under this location in the dataset tree. This value is only available when a
filesystem_limit has been set somewhere in the tree under which the
dataset resides.
logicalreferenced
The amount of space that is "logically"
accessible by this dataset. See the referenced property. The logical
space ignores the effect of the compression and copies
properties, giving a quantity closer to the amount of data that applications
see. However, it does include space consumed by metadata.
This property can also be referred to by its shortened column name,
lrefer.
logicalused
The amount of space that is "logically"
consumed by this dataset and all its descendents. See the used
property. The logical space ignores the effect of the compression and
copies properties, giving a quantity closer to the amount of data that
applications see. However, it does include space consumed by metadata.
This property can also be referred to by its shortened column name,
lused.
mounted
For file systems, indicates whether the file system is
currently mounted. This property can be either yes or no.
origin
For cloned file systems or volumes, the snapshot from
which the clone was created. See also the clones property.
referenced
The amount of data that is accessible by this dataset,
which may or may not be shared with other datasets in the pool. When a
snapshot or clone is created, it initially references the same amount of space
as the file system or snapshot it was created from, since its contents are
identical.
This property can also be referred to by its shortened column name,
refer.
refcompressratio
The compression ratio achieved for the referenced
space of this dataset, expressed as a multiplier. See also the
compressratio property.
snapshot_count
The total number of snapshots that exist under this
location in the dataset tree. This value is only available when a
snapshot_limit has been set somewhere in the tree under which the
dataset resides.
type
The type of dataset: filesystem, volume, or
snapshot.
used
The amount of space consumed by this dataset and all its
descendents. This is the value that is checked against this dataset's quota
and reservation. The space used does not include this dataset's reservation,
but does take into account the reservations of any descendent datasets. The
amount of space that a dataset consumes from its parent, as well as the amount
of space that are freed if this dataset is recursively destroyed, is the
greater of its space used and its reservation.
When snapshots (see the "Snapshots" section) are created, their space
is initially shared between the snapshot and the file system, and possibly
with previous snapshots. As the file system changes, space that was previously
shared becomes unique to the snapshot, and counted in the snapshot's space
used. Additionally, deleting snapshots can increase the amount of space unique
to (and used by) other snapshots.
The amount of space used, available, or referenced does not take into account
pending changes. Pending changes are generally accounted for within a few
seconds. Committing a change to a disk using fsync(2) or O_SYNC
does not necessarily guarantee that the space usage information is updated
immediately.
usedby*
The usedby* properties decompose the used
properties into the various reasons that space is used. Specifically,
used = usedbychildren + usedbydataset +
usedbyrefreservation +, usedbysnapshots. These properties are
only available for datasets created on zpool "version 13"
pools.
usedbychildren
The amount of space used by children of this dataset,
which would be freed if all the dataset's children were destroyed.
usedbydataset
The amount of space used by this dataset itself, which
would be freed if the dataset were destroyed (after first removing any
refreservation and destroying any necessary snapshots or
descendents).
usedbyrefreservation
The amount of space used by a refreservation set
on this dataset, which would be freed if the refreservation was
removed.
usedbysnapshots
The amount of space consumed by snapshots of this
dataset. In particular, it is the amount of space that would be freed if all
of this dataset's snapshots were destroyed. Note that this is not simply the
sum of the snapshots' used properties because space can be shared by
multiple snapshots.
userused@user
The amount of space consumed by the specified user in
this dataset. Space is charged to the owner of each file, as displayed by
ls -l. The amount of space charged is displayed by du and
ls -s. See the zfs userspace subcommand for more
information.
Unprivileged users can access only their own space usage. The root user, or a
user who has been granted the userused privilege with zfs allow,
can access everyone's usage.
The userused@... properties are not displayed by zfs get all. The
user's name must be appended after the @ symbol, using one of the
following forms:
userrefs
- o
- POSIX name (for example, joe)
- o
- POSIX numeric ID (for example, 789)
- o
- SID name (for example, joe.smith@mydomain)
- o
- SID numeric ID (for example, S-1-123-456-789)
This property is set to the number of user holds on this
snapshot. User holds are set by using the zfs hold command.
groupused@group
The amount of space consumed by the specified group in
this dataset. Space is charged to the group of each file, as displayed by
ls -l. See the userused@user property for more
information.
Unprivileged users can only access their own groups' space usage. The root user,
or a user who has been granted the groupused privilege with zfs
allow, can access all groups' usage.
volblocksize=blocksize
For volumes, specifies the block size of the volume. The
blocksize cannot be changed once the volume has been written, so it
should be set at volume creation time. The default blocksize for
volumes is 8 Kbytes. Any power of 2 from 512 bytes to 128 Kbytes is valid.
This property can also be referred to by its shortened column name,
volblock.
written
The amount of referenced space written to this
dataset since the previous snapshot.
written@snapshot
The amount of referenced space written to this
dataset since the specified snapshot. This is the space that is referenced by
this dataset but was not referenced by the specified snapshot.
The snapshot may be specified as a short snapshot name (just the part
after the @), in which case it will be interpreted as a snapshot in the
same filesystem as this dataset. The snapshot be a full snapshot name
(filesystem@snapshot), which for clones may be a snapshot in the
origin's filesystem (or the origin of the origin's filesystem, etc).
The following native properties can be used to change the behavior of a
ZFS dataset.
aclinherit=discard | noallow | restricted |
passthrough | passthrough-x
Controls how ACL entries are inherited when files
and directories are created. A file system with an aclinherit property
of discard does not inherit any ACL entries. A file system with
an aclinherit property value of noallow only inherits
inheritable ACL entries that specify "deny" permissions. The
property value restricted (the default) removes the write_acl
and write_owner permissions when the ACL entry is inherited. A
file system with an aclinherit property value of passthrough
inherits all inheritable ACL entries without any modifications made to
the ACL entries when they are inherited. A file system with an
aclinherit property value of passthrough-x has the same meaning
as passthrough, except that the owner@, group@, and
everyone@ ACEs inherit the execute permission only if the file
creation mode also requests the execute bit.
When the property value is set to passthrough, files are created with a
mode determined by the inheritable ACEs. If no inheritable ACEs
exist that affect the mode, then the mode is set in accordance to the
requested mode from the application.
The aclinherit property does not apply to Posix ACLs.
acltype=noacl | posixacl
Controls whether ACLs are enabled and if so what type of
ACL to use. When a file system has the acltype property set to
noacl (the default) then ACLs are disabled. Setting the acltype
property to posixacl indicates Posix ACLs should be used. Posix ACLs
are specific to Linux and are not functional on other platforms. Posix ACLs
are stored as an xattr and therefore will not overwrite any existing ZFS/NFSv4
ACLs which may be set. Currently only posixacls are supported on Linux.
To obtain the best performance when setting posixacl users are strongly
encouraged to set the xattr=sa property. This will result in the Posix
ACL being stored more efficiently on disk. But as a consequence of this all
new xattrs will only be accessible from ZFS implementations which support the
xattr=sa property. See the xattr property for more
details.
atime=on | off
Controls whether the access time for files is updated
when they are read. Turning this property off avoids producing write traffic
when reading files and can result in significant performance gains, though it
might confuse mailers and other similar utilities. The default value is
on. See also relatime below.
canmount=on | off | noauto
If this property is set to off, the file system
cannot be mounted, and is ignored by zfs mount -a. Setting this
property to off is similar to setting the mountpoint property to
none, except that the dataset still has a normal mountpoint
property, which can be inherited. Setting this property to off allows
datasets to be used solely as a mechanism to inherit properties. One example
of setting canmount=off is to have two datasets with the same
mountpoint, so that the children of both datasets appear in the same
directory, but might have different inherited characteristics.
When the noauto option is set, a dataset can only be mounted and
unmounted explicitly. The dataset is not mounted automatically when the
dataset is created or imported, nor is it mounted by the zfs mount -a
command or unmounted by the zfs unmount -a command.
This property is not inherited.
checksum=on | off | fletcher2,|
fletcher4 | sha256
Controls the checksum used to verify data integrity. The
default value is on, which automatically selects an appropriate
algorithm (currently, fletcher4, but this may change in future
releases). The value off disables integrity checking on user data.
Disabling checksums is NOT a recommended practice.
Changing this property affects only newly-written data.
compression=on | off | lzjb | lz4 |
gzip | gzip-N | zle
Controls the compression algorithm used for this dataset.
Setting compression to on indicates that the current default compression
algorithm should be used. The default balances compression and decompression
speed, with compression ratio and is expected to work well on a wide variety
of workloads. Unlike all other settings for this property, on does not
select a fixed compression type. As new compression algorithms are added to
ZFS and enabled on a pool, the default compression algorithm may change. The
current default compression algorthm is either lzjb or, if the
lz4_compress feature is enabled, lz4.
The lzjb compression algorithm is optimized for performance while
providing decent data compression.
The lz4 compression algorithm is a high-performance replacement for the
lzjb algorithm. It features significantly faster compression and
decompression, as well as a moderately higher compression ratio than
lzjb, but can only be used on pools with the lz4_compress
feature set to enabled. See zpool-features(5) for details on ZFS
feature flags and the lz4_compress feature.
The gzip compression algorithm uses the same compression as the
gzip(1) command. You can specify the gzip level by using the
value gzip-N where N is an integer from 1 (fastest) to 9
(best compression ratio). Currently, gzip is equivalent to
gzip-6 (which is also the default for gzip(1)). The zle
compression algorithm compresses runs of zeros.
This property can also be referred to by its shortened column name
compress. Changing this property affects only newly-written data.
copies=1 | 2 | 3
Controls the number of copies of data stored for this
dataset. These copies are in addition to any redundancy provided by the pool,
for example, mirroring or RAID-Z. The copies are stored on different disks, if
possible. The space used by multiple copies is charged to the associated file
and dataset, changing the used property and counting against quotas and
reservations.
Changing this property only affects newly-written data. Therefore, set this
property at file system creation time by using the -o
copies=N option.
dedup=on | off | verify |
sha256[,verify]
Controls whether deduplication is in effect for a
dataset. The default value is off. The default checksum used for
deduplication is sha256 (subject to change). When dedup is
enabled, the dedup checksum algorithm overrides the checksum
property. Setting the value to verify is equivalent to specifying
sha256,verify.
If the property is set to verify, then, whenever two blocks have the same
signature, ZFS will do a byte-for-byte comparison with the existing block to
ensure that the contents are identical.
Unless necessary, deduplication should NOT be enabled on a system. See
Deduplication above.
devices=on | off
Controls whether device nodes can be opened on this file
system. The default value is on.
exec=on | off
Controls whether processes can be executed from within
this file system. The default value is on.
mlslabel=label | none
The mlslabel property is a sensitivity label that
determines if a dataset can be mounted in a zone on a system with Trusted
Extensions enabled. If the labeled dataset matches the labeled zone, the
dataset can be mounted and accessed from the labeled zone.
When the mlslabel property is not set, the default value is none.
Setting the mlslabel property to none is equivalent to removing
the property.
The mlslabel property can be modified only when Trusted Extensions is
enabled and only with appropriate privilege. Rights to modify it cannot be
delegated. When changing a label to a higher label or setting the initial
dataset label, the {PRIV_FILE_UPGRADE_SL} privilege is required. When
changing a label to a lower label or the default ( none), the
{PRIV_FILE_DOWNGRADE_SL} privilege is required. Changing the dataset to
labels other than the default can be done only when the dataset is not
mounted. When a dataset with the default label is mounted into a labeled-zone,
the mount operation automatically sets the mlslabel property to the
label of that zone.
When Trusted Extensions is not enabled, only datasets with the default
label ( none) can be mounted.
Zones are a Solaris feature and are not relevant on Linux.
filesystem_limit=count | none
Limits the number of filesystems and volumes that can
exist under this point in the dataset tree. The limit is not enforced if the
user is allowed to change the limit. Setting a filesystem_limit on a
descendent of a filesystem that already has a filesystem_limit does not
override the ancestor's filesystem_limit, but rather imposes an additional
limit. This feature must be enabled to be used (see
zpool-features(5)).
mountpoint=path | none | legacy
Controls the mount point used for this file system. See
the "Mount Points" section for more information on how this property
is used.
When the mountpoint property is changed for a file system, the file
system and any children that inherit the mount point are unmounted. If the new
value is legacy, then they remain unmounted. Otherwise, they are
automatically remounted in the new location if the property was previously
legacy or none, or if they were mounted before the property was
changed. In addition, any shared file systems are unshared and shared in the
new location.
nbmand=on | off
Controls whether the file system should be mounted with
nbmand (Non Blocking mandatory locks). This is used for CIFS
clients. Changes to this property only take effect when the file system is
umounted and remounted. See mount(8) for more information on
nbmand mounts.
primarycache=all | none | metadata
Controls what is cached in the primary cache (ARC). If
this property is set to all, then both user data and metadata is
cached. If this property is set to none, then neither user data nor
metadata is cached. If this property is set to metadata, then only
metadata is cached. The default value is all.
quota=size | none
Limits the amount of space a dataset and its descendents
can consume. This property enforces a hard limit on the amount of space used.
This includes all space consumed by descendents, including file systems and
snapshots. Setting a quota on a descendent of a dataset that already has a
quota does not override the ancestor's quota, but rather imposes an additional
limit.
Quotas cannot be set on volumes, as the volsize property acts as an
implicit quota.
snapshot_limit=count | none
Limits the number of snapshots that can be created on a
dataset and its descendents. Setting a snapshot_limit on a descendent of a
dataset that already has a snapshot_limit does not override the ancestor's
snapshot_limit, but rather imposes an additional limit. The limit is not
enforced if the user is allowed to change the limit. For example, this means
that recursive snapshots taken from the global zone are counted against each
delegated dataset within a zone. This feature must be enabled to be used (see
zpool-features(5)).
userquota@user=size | none
Limits the amount of space consumed by the specified
user. Similar to the refquota property, the userquota space
calculation does not include space that is used by descendent datasets, such
as snapshots and clones. User space consumption is identified by the
userspace@ user property.
Enforcement of user quotas may be delayed by several seconds. This delay means
that a user might exceed their quota before the system notices that they are
over quota and begins to refuse additional writes with the EDQUOT error
message . See the zfs userspace subcommand for more information.
Unprivileged users can only access their own groups' space usage. The root user,
or a user who has been granted the userquota privilege with zfs
allow, can get and set everyone's quota.
This property is not available on volumes, on file systems before version 4, or
on pools before version 15. The userquota@... properties are not
displayed by zfs get all. The user's name must be appended after the
@ symbol, using one of the following forms:
groupquota@group=size | none
- o
- POSIX name (for example, joe)
- o
- POSIX numeric ID (for example, 789)
- o
- SID name (for example, joe.smith@mydomain)
- o
- SID numeric ID (for example, S-1-123-456-789)
Limits the amount of space consumed by the specified
group. Group space consumption is identified by the
userquota@user property.
Unprivileged users can access only their own groups' space usage. The root user,
or a user who has been granted the groupquota privilege with zfs
allow, can get and set all groups' quotas.
readonly=on | off
Controls whether this dataset can be modified. The
default value is off.
This property can also be referred to by its shortened column name,
rdonly.
recordsize=size
Specifies a suggested block size for files in the file
system. This property is designed solely for use with database workloads that
access files in fixed-size records. ZFS automatically tunes block sizes
according to internal algorithms optimized for typical access patterns.
For databases that create very large files but access them in small random
chunks, these algorithms may be suboptimal. Specifying a recordsize
greater than or equal to the record size of the database can result in
significant performance gains. Use of this property for general purpose file
systems is strongly discouraged, and may adversely affect performance.
The size specified must be a power of two greater than or equal to 512 and less
than or equal to 128 Kbytes.
Changing the file system's recordsize affects only files created
afterward; existing files are unaffected.
This property can also be referred to by its shortened column name,
recsize.
redundant_metadata=all | most
Controls what types of metadata are stored redundantly.
ZFS stores an extra copy of metadata, so that if a single block is corrupted,
the amount of user data lost is limited. This extra copy is in addition to any
redundancy provided at the pool level (e.g. by mirroring or RAID-Z), and is in
addition to an extra copy specified by the copies property (up to a
total of 3 copies). For example if the pool is mirrored, copies=2, and
redundant_metadata=most, then ZFS stores 6 copies of most metadata, and
4 copies of data and some metadata.
When set to all, ZFS stores an extra copy of all metadata. If a single
on-disk block is corrupt, at worst a single block of user data (which is
recordsize bytes long) can be lost.
When set to most, ZFS stores an extra copy of most types of metadata.
This can improve performance of random writes, because less metadata must be
written. In practice, at worst about 100 blocks (of recordsize bytes
each) of user data can be lost if a single on-disk block is corrupt. The exact
behavior of which metadata blocks are stored redundantly may change in future
releases.
The default value is all.
refquota=size | none
Limits the amount of space a dataset can consume. This
property enforces a hard limit on the amount of space used. This hard limit
does not include space used by descendents, including file systems and
snapshots.
refreservation=size | none
The minimum amount of space guaranteed to a dataset, not
including its descendents. When the amount of space used is below this value,
the dataset is treated as if it were taking up the amount of space specified
by refreservation. The refreservation reservation is accounted
for in the parent datasets' space used, and counts against the parent
datasets' quotas and reservations.
If refreservation is set, a snapshot is only allowed if there is enough
free pool space outside of this reservation to accommodate the current number
of "referenced" bytes in the dataset.
This property can also be referred to by its shortened column name,
refreserv.
relatime=on | off
Controls the manner in which the access time is updated
when atime=on is set. Turning this property on causes the access
time to be updated relative to the modify or change time. Access time is only
updated if the previous access time was earlier than the current modify or
change time or if the existing access time hasn't been updated within the past
24 hours. The default value is off.
reservation=size | none
The minimum amount of space guaranteed to a dataset and
its descendents. When the amount of space used is below this value, the
dataset is treated as if it were taking up the amount of space specified by
its reservation. Reservations are accounted for in the parent datasets' space
used, and count against the parent datasets' quotas and reservations.
This property can also be referred to by its shortened column name,
reserv.
secondarycache=all | none | metadata
Controls what is cached in the secondary cache (L2ARC).
If this property is set to all, then both user data and metadata is
cached. If this property is set to none, then neither user data nor
metadata is cached. If this property is set to metadata, then only
metadata is cached. The default value is all.
setuid=on | off
Controls whether the set-UID bit is respected for
the file system. The default value is on.
shareiscsi=on | off
Like the sharenfs property, shareiscsi
indicates whether a ZFS volume is exported as an iSCSI target.
The acceptable values for this property are on, off, and
type=disk. The default value is off. In the future, other target
types might be supported. For example, tape.
You might want to set shareiscsi=on for a file system so that all
ZFS volumes within the file system are shared by default. However,
setting this property on a file system has no direct effect.
sharesmb=on | off
Controls whether the file system is shared by using
Samba USERSHARES, and what options are to be used. Otherwise, the file
system is automatically shared and unshared with the zfs share and
zfs unshare commands. If the property is set to on, the
net(8) command is invoked to create a USERSHARE.
Because SMB shares requires a resource name, a unique resource name is
constructed from the dataset name. The constructed name is a copy of the
dataset name except that the characters in the dataset name, which would be
illegal in the resource name, are replaced with underscore ( _)
characters. The ZFS On Linux driver does not (yet) support additional options
which might be available in the Solaris version.
If the sharesmb property is set to off, the file systems are
unshared.
In Linux, the share is created with the ACL (Access Control List)
"Everyone:F" ("F" stands for "full permissions",
ie. read and write permissions) and no guest access (which means samba must be
able to authenticate a real user, system passwd/shadow, ldap or smbpasswd
based) by default. This means that any additional access control (dissalow
specific user specific access etc) must be done on the underlaying filesystem.
Example to mount a SMB filesystem shared through ZFS (share/tmp): Note that a user and his/her password must be given!
smbmount //127.0.0.1/share_tmp /mnt/tmp -o user=workgroup/turbo,password=obrut,uid=1000
Minimal /etc/samba/smb.conf configuration
* Samba will need to listen to 'localhost' (127.0.0.1) for the zfs utilities to communitate with samba. This is the default behavior for most Linux distributions. * Samba must be able to authenticate a user. This can be done in a number of ways, depending on if using the system password file, LDAP or the Samba specific smbpasswd file. How to do this is outside the scope of this manual. Please refer to the smb.conf(5) manpage for more information. * See the USERSHARE section of the smb.conf(5) man page for all configuration options in case you need to modify any options to the share afterwards. Do note that any changes done with the 'net' command will be undone if the share is every unshared (such as at a reboot etc). In the future, ZoL will be able to set specific options directly using sharesmb=<option>.
sharenfs=on | off | opts
Example to mount a SMB filesystem shared through ZFS (share/tmp): Note that a user and his/her password must be given!
smbmount //127.0.0.1/share_tmp /mnt/tmp -o user=workgroup/turbo,password=obrut,uid=1000
Minimal /etc/samba/smb.conf configuration
* Samba will need to listen to 'localhost' (127.0.0.1) for the zfs utilities to communitate with samba. This is the default behavior for most Linux distributions. * Samba must be able to authenticate a user. This can be done in a number of ways, depending on if using the system password file, LDAP or the Samba specific smbpasswd file. How to do this is outside the scope of this manual. Please refer to the smb.conf(5) manpage for more information. * See the USERSHARE section of the smb.conf(5) man page for all configuration options in case you need to modify any options to the share afterwards. Do note that any changes done with the 'net' command will be undone if the share is every unshared (such as at a reboot etc). In the future, ZoL will be able to set specific options directly using sharesmb=<option>.
Controls whether the file system is shared via
NFS, and what options are used. A file system with a sharenfs
property of off is managed with the exportfs(8) command and
entries in /etc/exports file. Otherwise, the file system is
automatically shared and unshared with the zfs share and zfs
unshare commands. If the property is set to on, the dataset is
shared using the exportfs(8) command in the following manner (see
exportfs(8) for the meaning of the different options):
Otherwise, the exportfs(8) command is invoked with options equivalent to the contents of this property. When the sharenfs property is changed for a dataset, the dataset and any children inheriting the property are re-shared with the new options, only if the property was previously off, or if they were shared before the property was changed. If the new property is off, the file systems are unshared.
logbias = latency | throughput
/usr/sbin/exportfs -i -o sec=sys,rw,no_subtree_check,no_root_squash,mountpoint *:<mountpoint of dataset>
Otherwise, the exportfs(8) command is invoked with options equivalent to the contents of this property. When the sharenfs property is changed for a dataset, the dataset and any children inheriting the property are re-shared with the new options, only if the property was previously off, or if they were shared before the property was changed. If the new property is off, the file systems are unshared.
Provide a hint to ZFS about handling of synchronous
requests in this dataset. If logbias is set to latency (the
default), ZFS will use pool log devices (if configured) to handle the requests
at low latency. If logbias is set to throughput, ZFS will not
use configured pool log devices. ZFS will instead optimize synchronous
operations for global pool throughput and efficient use of resources.
snapdev=hidden | visible
Controls whether the snapshots devices of zvol's are
hidden or visible. The default value is hidden.
snapdir=hidden | visible
Controls whether the .zfs directory is hidden or
visible in the root of the file system as discussed in the
"Snapshots" section. The default value is hidden.
sync=standard | always | disabled
Controls the behavior of synchronous requests (e.g.
fsync, O_DSYNC). standard is the POSIX specified behavior of ensuring
all synchronous requests are written to stable storage and all devices are
flushed to ensure data is not cached by device controllers (this is the
default). always causes every file system transaction to be written and
flushed before its system call returns. This has a large performance penalty.
disabled disables synchronous requests. File system transactions are
only committed to stable storage periodically. This option will give the
highest performance. However, it is very dangerous as ZFS would be ignoring
the synchronous transaction demands of applications such as databases or NFS.
Administrators should only use this option when the risks are
understood.
version=1 | 2 | current
The on-disk version of this file system, which is
independent of the pool version. This property can only be set to later
supported versions. See the zfs upgrade command.
volsize=size
For volumes, specifies the logical size of the volume. By
default, creating a volume establishes a reservation of equal size. For
storage pools with a version number of 9 or higher, a refreservation is
set instead. Any changes to volsize are reflected in an equivalent
change to the reservation (or refreservation). The volsize can
only be set to a multiple of volblocksize, and cannot be zero.
The reservation is kept equal to the volume's logical size to prevent unexpected
behavior for consumers. Without the reservation, the volume could run out of
space, resulting in undefined behavior or data corruption, depending on how
the volume is used. These effects can also occur when the volume size is
changed while it is in use (particularly when shrinking the size). Extreme
care should be used when adjusting the volume size.
Though not recommended, a "sparse volume" (also known as "thin
provisioning") can be created by specifying the -s option to the
zfs create -V command, or by changing the reservation after the volume
has been created. A "sparse volume" is a volume where the
reservation is less then the volume size. Consequently, writes to a sparse
volume can fail with ENOSPC when the pool is low on space. For a sparse
volume, changes to volsize are not reflected in the reservation.
vscan=on | off
Controls whether regular files should be scanned for
viruses when a file is opened and closed. In addition to enabling this
property, the virus scan service must also be enabled for virus scanning to
occur. The default value is off.
xattr=on | off | sa
Controls whether extended attributes are enabled for this
file system. Two styles of extended attributes are supported either directory
based or system attribute based.
The default value of on enables directory based extended attributes. This
style of xattr imposes no practical limit on either the size or number of
xattrs which may be set on a file. Although under Linux the getxattr(2)
and setxattr(2) system calls limit the maximum xattr size to 64K. This
is the most compatible style of xattr and it is supported by the majority of
ZFS implementations.
System attribute based xattrs may be enabled by setting the value to sa.
The key advantage of this type of xattr is improved performance. Storing
xattrs as system attributes significantly decreases the amount of disk IO
required. Up to 64K of xattr data may be stored per file in the space reserved
for system attributes. If there is not enough space available for an xattr
then it will be automatically written as a directory based xattr. System
attribute based xattrs are not accessible on platforms which do not support
the xattr=sa feature.
The use of system attribute based xattrs is strongly encouraged for users of
SELinux or Posix ACLs. Both of these features heavily rely of xattrs and
benefit significantly from the reduced xattr access time.
zoned=on | off
Controls whether the dataset is managed from a non-global
zone. Zones are a Solaris feature and are not relevant on Linux. The default
value is off.
The following three properties cannot be changed after the file system is
created, and therefore, should be set when the file system is created. If the
properties are not set with the zfs create or zpool create
commands, these properties are inherited from the parent dataset. If the
parent dataset lacks these properties due to having been created prior to
these features being supported, the new file system will have the default
values for these properties.
casesensitivity=sensitive | insensitive |
mixed
Indicates whether the file name matching algorithm used
by the file system should be case-sensitive, case-insensitive, or allow a
combination of both styles of matching. The default value for the
casesensitivity property is sensitive. Traditionally, UNIX and
POSIX file systems have case-sensitive file names.
The mixed value for the casesensitivity property indicates that
the file system can support requests for both case-sensitive and
case-insensitive matching behavior. Currently, case-insensitive matching
behavior on a file system that supports mixed behavior is limited to the
Solaris CIFS server product. For more information about the mixed value
behavior, see the Solaris ZFS Administration Guide.
normalization = none | formC | formD |
formKC | formKD
Indicates whether the file system should perform a
unicode normalization of file names whenever two file names are
compared, and which normalization algorithm should be used. File names are
always stored unmodified, names are normalized as part of any comparison
process. If this property is set to a legal value other than none, and
the utf8only property was left unspecified, the utf8only
property is automatically set to on. The default value of the
normalization property is none. This property cannot be changed
after the file system is created.
utf8only=on | off
Indicates whether the file system should reject file
names that include characters that are not present in the UTF-8
character code set. If this property is explicitly set to off, the
normalization property must either not be explicitly set or be set to
none. The default value for the utf8only property is off.
This property cannot be changed after the file system is created.
The casesensitivity, normalization, and utf8only properties
are also new permissions that can be assigned to non-privileged users by using
the ZFS delegated administration feature.
context=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for all files in the
filesytem under the mountpoint for that filesystem. See selinux(8) for
more information.
fscontext=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for the filesytem
being mounted. See selinux(8) for more information.
defntext=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for unlabeled files.
See selinux(8) for more information.
rootcontext=SELinux_User:SElinux_Role:Selinux_Type:Sensitivity_Level
This flag sets the SELinux context for the root inode of
the filesystem. See selinux(8) for more information.
overlay=on | off
Allow mounting on a busy directory or a directory which
already contains files/directories. This is the default mount behavior for
Linux filesystems. However, for consistency with ZFS on other platforms
overlay mounts are disabled by default. Set overlay=on to enable
overlay mounts.
Temporary Mount Point Properties¶
When a file system is mounted, either through mount(8) for legacy mounts or the zfs mount command for normal file systems, its mount options are set according to its properties. The correlation between properties and mount options is as follows:PROPERTY MOUNT OPTION devices devices/nodevices exec exec/noexec readonly ro/rw setuid setuid/nosetuid xattr xattr/noxattr atime atime/noatime relatime relatime/norelatime nbmand nbmand/nonbmand
In addition, these options can be set on a per-mount basis using the -o option, without affecting the property that is stored on disk. The values specified on the command line override the values stored in the dataset. The -nosuid option is an alias for nodevices,nosetuid. These properties are reported as "temporary" by the zfs get command. If the properties are changed while the dataset is mounted, the new setting overrides any temporary settings.
User Properties¶
In addition to the standard native properties, ZFS supports arbitrary user properties. User properties have no effect on ZFS behavior, but applications or administrators can use them to annotate datasets (file systems, volumes, and snapshots). User property names must contain a colon ( :) character to distinguish them from native properties. They may contain lowercase letters, numbers, and the following punctuation characters: colon ( :), dash (-), period ( .), and underscore (_). The expected convention is that the property name is divided into two portions such as module:property, but this namespace is not enforced by ZFS. User property names can be at most 256 characters, and cannot begin with a dash ( -). When making programmatic use of user properties, it is strongly suggested to use a reversed DNS domain name for the module component of property names to reduce the chance that two independently-developed packages use the same property name for different purposes. For example, property names beginning with com.sun. are reserved for use by Oracle Corporation (which acquired Sun Microsystems). The values of user properties are arbitrary strings, are always inherited, and are never validated. All of the commands that operate on properties ( zfs list, zfs get, zfs set, and so forth) can be used to manipulate both native properties and user properties. Use the zfs inherit command to clear a user property . If the property is not defined in any parent dataset, it is removed entirely. Property values are limited to 1024 characters.ZFS Volumes as Swap¶
ZFS volumes may be used as Linux swap devices. After creating the volume with the zfs create command set up and enable the swap area using the mkswap(8) and swapon(8) commands. Do not swap to a file on a ZFS file system. A ZFS swap file configuration is not supported.SUBCOMMANDS¶
All subcommands that modify state are logged persistently to the pool in their original form. zfs ?Displays a help message.
zfs create [-p] [-o property=value]
... filesystem
Creates a new ZFS file system. The file system is
automatically mounted according to the mountpoint property inherited
from the parent.
-p
zfs create [-ps] [-b blocksize] [-o
property=value] ... -V size volume
Creates all the non-existing parent datasets. Datasets
created in this manner are automatically mounted according to the
mountpoint property inherited from their parent. Any property specified
on the command line using the -o option is ignored. If the target
filesystem already exists, the operation completes successfully.
-o property=value
Sets the specified property as if the command zfs
set property=value was invoked at the same time the dataset
was created. Any editable ZFS property can also be set at creation
time. Multiple -o options can be specified. An error results if the
same property is specified in multiple -o options.
Creates a volume of the given size. The volume is
exported as a block device in /dev/zvol/path, where path
is the name of the volume in the ZFS namespace. The size represents the
logical size as exported by the device. By default, a reservation of equal
size is created.
size is automatically rounded up to the nearest 128 Kbytes to ensure that
the volume has an integral number of blocks regardless of blocksize.
-p
zfs destroy [-fnpRrv] filesystem|volume
Creates all the non-existing parent datasets. Datasets
created in this manner are automatically mounted according to the
mountpoint property inherited from their parent. Any property specified
on the command line using the -o option is ignored. If the target
filesystem already exists, the operation completes successfully.
-s
Creates a sparse volume with no reservation. See
volsize in the Native Properties section for more information about
sparse volumes.
-o property=value
Sets the specified property as if the zfs set
property= value command was invoked at the same time the dataset
was created. Any editable ZFS property can also be set at creation
time. Multiple -o options can be specified. An error results if the
same property is specified in multiple -o options.
-b blocksize
Equivalent to -o
volblocksize=blocksize. If this option is specified in
conjunction with -o volblocksize, the resulting behavior is
undefined.
Destroys the given dataset. By default, the command
unshares any file systems that are currently shared, unmounts any file systems
that are currently mounted, and refuses to destroy a dataset that has active
dependents (children or clones).
-r
zfs destroy [-dnpRrv]
filesystem|volume@snap[% snap][,...]
Recursively destroy all children.
-R
Recursively destroy all dependents, including cloned file
systems outside the target hierarchy.
-f
Force an unmount of any file systems using the unmount
-f command. This option has no effect on non-file systems or unmounted
file systems.
-n
Do a dry-run ("No-op") deletion. No data will
be deleted. This is useful in conjunction with the -v or -p
flags to determine what data would be deleted.
-p
Print machine-parsable verbose information about the
deleted data.
-v
Print verbose information about the deleted data.
Extreme care should be taken when applying either the -r or the -R
options, as they can destroy large portions of a pool and cause unexpected
behavior for mounted file systems in use.The given snapshots are destroyed immediately if and only
if the zfs destroy command without the -d option would have
destroyed it. Such immediate destruction would occur, for example, if the
snapshot had no clones and the user-initiated reference count were zero.
If a snapshot does not qualify for immediate destruction, it is marked for
deferred destruction. In this state, it exists as a usable, visible snapshot
until both of the preconditions listed above are met, at which point it is
destroyed.
An inclusive range of snapshots may be specified by separating the first and
last snapshots with a percent sign. The first and/or last snapshots may be
left blank, in which case the filesystem's oldest or newest snapshot will be
implied.
Multiple snapshots (or ranges of snapshots) of the same filesystem or volume may
be specified in a comma-separated list of snapshots. Only the snapshot's short
name (the part after the @) should be specified when using a range or
comma-separated list to identify multiple snapshots.
-d
zfs destroy filesystem|volume#bookmark
Defer snapshot deletion.
-r
Destroy (or mark for deferred destruction) all snapshots
with this name in descendent file systems.
-R
Recursively destroy all clones of these snapshots,
including the clones, snapshots, and children. If this flag is specified, the
-d flag will have no effect.
-n
Do a dry-run ("No-op") deletion. No data will
be deleted. This is useful in conjunction with the -v or -p
flags to determine what data would be deleted.
-p
Print machine-parsable verbose information about the
deleted data.
-v
Print verbose information about the deleted data.
Extreme care should be taken when applying either the -r or the -R
options, as they can destroy large portions of a pool and cause unexpected
behavior for mounted file systems in use.The given bookmark is destroyed.
zfs snapshot [-r] [-o property=value]
... filesystem@snapname|volume@snapname ...
Creates snapshots with the given names. All previous
modifications by successful system calls to the file system are part of the
snapshots. Snapshots are taken atomically, so that all snapshots correspond to
the same moment in time. See the "Snapshots" section for details.
-r
zfs rollback [-rRf] snapshot
Recursively create snapshots of all descendent
datasets.
-o property=value
Sets the specified property; see zfs create for
details.
Roll back the given dataset to a previous snapshot. When
a dataset is rolled back, all data that has changed since the snapshot is
discarded, and the dataset reverts to the state at the time of the snapshot.
By default, the command refuses to roll back to a snapshot other than the most
recent one. In order to do so, all intermediate snapshots and bookmarks must
be destroyed by specifying the -r option.
The -rR options do not recursively destroy the child snapshots of a
recursive snapshot. Only direct snapshots of the specified filesystem are
destroyed by either of these options. To completely roll back a recursive
snapshot, you must rollback the individual child snapshots.
-r
zfs clone [-p] [-o property=value] ...
snapshot filesystem|volume
Destroy any snapshots and bookmarks more recent than the
one specified.
-R
Recursively destroy any more recent snapshots and
bookmarks, as well as any clones of those snapshots.
-f
Used with the -R option to force an unmount of any
clone file systems that are to be destroyed.
Creates a clone of the given snapshot. See the
"Clones" section for details. The target dataset can be located
anywhere in the ZFS hierarchy, and is created as the same type as the
original.
-p
zfs promote clone-filesystem
Creates all the non-existing parent datasets. Datasets
created in this manner are automatically mounted according to the
mountpoint property inherited from their parent. If the target
filesystem or volume already exists, the operation completes
successfully.
-o property=value
Sets the specified property; see zfs create for
details.
Promotes a clone file system to no longer be dependent on
its "origin" snapshot. This makes it possible to destroy the file
system that the clone was created from. The clone parent-child dependency
relationship is reversed, so that the origin file system becomes a clone of
the specified file system.
The snapshot that was cloned, and any snapshots previous to this snapshot, are
now owned by the promoted clone. The space they use moves from the origin file
system to the promoted clone, so enough space must be available to accommodate
these snapshots. No new space is consumed by this operation, but the space
accounting is adjusted. The promoted clone must not have any conflicting
snapshot names of its own. The rename subcommand can be used to rename
any conflicting snapshots.
zfs rename [-f]
filesystem|volume|snapshot
Renames the given dataset. The new target can be located
anywhere in the ZFS hierarchy, with the exception of snapshots.
Snapshots can only be renamed within the parent file system or volume. When
renaming a snapshot, the parent file system of the snapshot does not need to
be specified as part of the second argument. Renamed file systems can inherit
new mount points, in which case they are unmounted and remounted at the new
mount point.
-p
zfs rename -r snapshot snapshot
Creates all the nonexistent parent datasets. Datasets
created in this manner are automatically mounted according to the
mountpoint property inherited from their parent.
-f
Force unmount any filesystems that need to be unmounted
in the process.
Recursively rename the snapshots of all descendent
datasets. Snapshots are the only dataset that can be renamed
recursively.
zfs list [-r|-d depth] [-Hp]
[-o property[,...]] [ -t type[,...]]
[ -s property ] ... [ -S property ] ...
[filesystem| volume|snapshot] ...
Lists the property information for the given datasets in
tabular form. If specified, you can list property information by the absolute
pathname or the relative pathname. By default, all file systems and volumes
are displayed. Snapshots are displayed if the listsnaps property is
on (the default is off). When listing hundreds or thousands of
snapshots performance can be improved by restricting the output to only the
name. In that case, it is recommended to use -o name -s name. The
following fields are displayed by default,
name,used,available,referenced,mountpoint.
-H
zfs set property=value
filesystem|volume| snapshot ...
Used for scripting mode. Do not print headers and
separate fields by a single tab instead of arbitrary white space.
-p
Display numbers in parsable (exact) values.
-r
Recursively display any children of the dataset on the
command line.
-d depth
Recursively display any children of the dataset, limiting
the recursion to depth. A depth of 1 will display only the
dataset and its direct children.
-o property
A comma-separated list of properties to display. The
property must be:
-s property
- o
- One of the properties described in the "Native Properties" section
- o
- A user property
- o
- The value name to display the dataset name
- o
- The value space to display space usage properties on file systems and volumes. This is a shortcut for specifying -o name,avail,used,usedsnap,usedds,usedrefreserv,usedchild -t filesystem,volume syntax.
A property for sorting the output by column in ascending
order based on the value of the property. The property must be one of the
properties described in the "Properties" section, or the special
value name to sort by the dataset name. Multiple properties can be
specified at one time using multiple -s property options. Multiple
-s options are evaluated from left to right in decreasing order of
importance.
The following is a list of sorting criteria:
-S property
- o
- Numeric types sort in numeric order.
- o
- String types sort in alphabetical order.
- o
- Types inappropriate for a row sort that row to the literal bottom, regardless of the specified ordering.
- o
- If no sorting options are specified the existing behavior of zfs list is preserved.
Same as the -s option, but sorts by property in
descending order.
-t type
A comma-separated list of types to display, where
type is one of filesystem, snapshot, snap,
volume, bookmark, or all. For example, specifying -t
snapshot displays only snapshots.
Sets the property to the given value for each dataset.
Only some properties can be edited. See the "Properties" section for
more information on what properties can be set and acceptable values. Numeric
values can be specified as exact values, or in a human-readable form with a
suffix of B, K, M, G, T, P,
E, Z (for bytes, kilobytes, megabytes, gigabytes, terabytes,
petabytes, exabytes, or zettabytes, respectively). User properties can be set
on snapshots. For more information, see the "User Properties"
section.
zfs get [-r|-d depth] [-Hp] [-o
field[,...] [-t type[,...]] [-s
source[,...] " all" | property[,...]
filesystem| volume|snapshot ...
Displays properties for the given datasets. If no
datasets are specified, then the command displays properties for all datasets
on the system. For each property, the following columns are displayed:
All columns are displayed by default, though this can be controlled by using the -o option. This command takes a comma-separated list of properties as described in the "Native Properties" and "User Properties" sections. The special value all can be used to display all properties that apply to the given dataset's type (filesystem, volume snapshot, or bookmark). -r
zfs inherit [-rS] property
filesystem|volume| snapshot ...
name Dataset name property Property name value Property value source Property source. Can either be local, default, temporary, inherited, received, or none (-).
All columns are displayed by default, though this can be controlled by using the -o option. This command takes a comma-separated list of properties as described in the "Native Properties" and "User Properties" sections. The special value all can be used to display all properties that apply to the given dataset's type (filesystem, volume snapshot, or bookmark). -r
Recursively display properties for any children.
-d depth
Recursively display any children of the dataset, limiting
the recursion to depth. A depth of 1 will display only the
dataset and its direct children.
-H
Display output in a form more easily parsed by scripts.
Any headers are omitted, and fields are explicitly separated by a single tab
instead of an arbitrary amount of space.
-o field
A comma-separated list of columns to display.
name,property,value,source is the default value.
-s source
A comma-separated list of sources to display. Those
properties coming from a source other than those in this list are ignored.
Each source must be one of the following:
local,default,inherited,received,temporary,none. The default value is
all sources.
-p
Display numbers in parsable (exact) values.
Clears the specified property, causing it to be inherited
from an ancestor, restored to default if no ancestor has the property set, or
with the -S option reverted to the received value if one exists. See
the "Properties" section for a listing of default values, and
details on which properties can be inherited.
-r
zfs upgrade [-v]
Recursively inherit the given property for all
children.
-S
Revert the property to the received value if one exists;
otherwise operate as if the -S option was not specified.
Displays a list of file systems that are not the most
recent version.
zfs upgrade [-r] [-V version] [-a |
filesystem]
Upgrades file systems to a new on-disk version. Once this
is done, the file systems will no longer be accessible on systems running
older versions of the software. zfs send streams generated from new
snapshots of these file systems cannot be accessed on systems running older
versions of the software.
In general, the file system version is independent of the pool version. See
zpool(8) for information on the zpool upgrade command.
In some cases, the file system version and the pool version are interrelated and
the pool version must be upgraded before the file system version can be
upgraded.
-a
zfs userspace [-Hinp] [-o field[,...]] [
-s field] ... [ -S field] ... [ -t
type[,...]] filesystem|snapshot
Upgrade all file systems on all imported pools.
filesystem
Upgrade the specified file system.
-r
Upgrade the specified file system and all descendent file
systems
-V version
Upgrade to the specified version. If the -V
flag is not specified, this command upgrades to the most recent version. This
option can only be used to increase the version number, and only up to the
most recent version supported by this software.
Displays space consumed by, and quotas on, each user in
the specified filesystem or snapshot. This corresponds to the
userused@user and userquota@user properties.
-n
zfs groupspace [-Hinp] [-o field[,...]] [
-s field] ... [ -S field] ... [ -t
type[,...]] filesystem|snapshot
Print numeric ID instead of user/group name.
-H
Do not print headers, use tab-delimited output.
-p
Use exact (parsable) numeric output.
-o field[,...]
Display only the specified fields from the following set:
type, name, used, quota. The default is to display all fields.
-s field
Sort output by this field. The s and S
flags may be specified multiple times to sort first by one field, then by
another. The default is -s type -s name.
-S field
Sort by this field in reverse order. See -s.
-t type[,...]
Print only the specified types from the following set:
all, posixuser, smbuser, posixgroup, smbgroup. The default is -t
posixuser,smbuser. The default can be changed to include group
types.
-i
Translate SID to POSIX ID. The POSIX ID may be ephemeral
if no mapping exists. Normal POSIX interfaces (for example, stat(2),
ls -l) perform this translation, so the -i option allows
the output from zfs userspace to be compared directly with those
utilities. However, -i may lead to confusion if some files were created
by an SMB user before a SMB-to-POSIX name mapping was established. In such a
case, some files will be owned by the SMB entity and some by the POSIX entity.
However, the -i option will report that the POSIX entity has the total
usage and quota for both.
Displays space consumed by, and quotas on, each group in
the specified filesystem or snapshot. This subcommand is identical to zfs
userspace, except that the default types to display are -t
posixgroup,smbgroup.
zfs mount
Displays all ZFS file systems currently
mounted.
zfs mount [-vO] [-o options] -a |
filesystem
Mounts ZFS file systems. Invoked automatically as
part of the boot process.
-o options
zfs unmount [-f] -a |
filesystem|mountpoint
An optional, comma-separated list of mount options to use
temporarily for the duration of the mount. See the "Temporary Mount Point
Properties" section for details.
-O
Perform an overlay mount. See mount(8) for more
information.
-v
Report mount progress.
-a
Mount all available ZFS file systems. Invoked
automatically as part of the boot process.
filesystem
Mount the specified filesystem.
Unmounts currently mounted ZFS file systems.
Invoked automatically as part of the shutdown process.
-f
zfs share -a | filesystem
Forcefully unmount the file system, even if it is
currently in use.
-a
Unmount all available ZFS file systems. Invoked
automatically as part of the boot process.
filesystem|mountpoint
Unmount the specified filesystem. The command can also be
given a path to a ZFS file system mount point on the system.
Shares available ZFS file systems.
-a
zfs unshare -a | filesystem|mountpoint
Share all available ZFS file systems. Invoked
automatically as part of the boot process.
filesystem
Share the specified filesystem according to the
sharenfs and sharesmb properties. File systems are shared when
the sharenfs or sharesmb property is set.
Unshares currently shared ZFS file systems. This
is invoked automatically as part of the shutdown process.
-a
zfs bookmark snapshot bookmark
Unshare all available ZFS file systems. Invoked
automatically as part of the boot process.
filesystem|mountpoint
Unshare the specified filesystem. The command can also be
given a path to a ZFS file system shared on the system.
Creates a bookmark of the given snapshot. Bookmarks mark
the point in time when the snapshot was created, and can be used as the
incremental source for a zfs send command.
This feature must be enabled to be used. See zpool-features(5) for
details on ZFS feature flags and the bookmarks feature.
zfs send [-DnPpRveL] [-[iI] snapshot]
snapshot
Creates a stream representation of the second
snapshot, which is written to standard output. The output can be
redirected to a file or to a different system (for example, using
ssh(1). By default, a full stream is generated.
-i snapshot
zfs send [-eL] [-i snapshot|bookmark]
filesystem| volume|snapshot
Generate an incremental stream from the first
snapshot (the incremental source) to the second snapshot (the
incremental target). The incremental source can be specified as the last
component of the snapshot name (the @ character and following) and it
is assumed to be from the same file system as the incremental target.
If the destination is a clone, the source may be the origin snapshot, which must
be fully specified (for example, pool/fs@origin, not just
@origin).
-I snapshot
Generate a stream package that sends all intermediary
snapshots from the first snapshot to the second snapshot. For example, -I
@a fs@d is similar to -i @a fs@b; -i @b fs@c; -i @c fs@d. The
incremental source may be specified as with the -i option.
-R
Generate a replication stream package, which will
replicate the specified filesystem, and all descendent file systems, up to the
named snapshot. When received, all properties, snapshots, descendent file
systems, and clones are preserved.
If the -i or -I flags are used in conjunction with the -R
flag, an incremental replication stream is generated. The current values of
properties, and current snapshot and file system names are set when the stream
is received. If the -F flag is specified when this stream is received,
snapshots and file systems that do not exist on the sending side are
destroyed.
-D
Generate a deduplicated stream. Blocks which would have
been sent multiple times in the send stream will only be sent once. The
receiving system must also support this feature to receive a deduplicated
stream. This flag can be used regardless of the dataset's dedup property, but
performance will be much better if the filesystem uses a dedup-capable
checksum (eg. sha256).
-L
Generate a stream which may contain blocks larger than
128KB. This flag has no effect if the large_blocks pool feature is
disabled, or if the recordsize property of this filesystem has never been set
above 128KB. The receiving system must have the large_blocks pool
feature enabled as well. See zpool-features(5) for details on ZFS
feature flags and the large_blocks feature.
-e
Generate a more compact stream by using WRITE_EMBEDDED
records for blocks which are stored more compactly on disk by the
embedded_data pool feature. This flag has no effect if the
embedded_data feature is disabled. The receiving system must have the
embedded_data feature enabled. If the lz4_compress feature is
active on the sending system, then the receiving system must have that feature
enabled as well. See zpool-features(5) for details on ZFS feature flags
and the embedded_data feature.
-p
Include the dataset's properties in the stream. This flag
is implicit when -R is specified. The receiving system must also support this
feature.
-n
Do a dry-run ("No-op") send. Do not generate
any actual send data. This is useful in conjunction with the -v or
-P flags to determine what data will be sent. In this case, the verbose
output will be written to standard output (contrast with a non-dry-run, where
the stream is written to standard output and the verbose output goes to
standard error).
-P
Print machine-parsable verbose information about the
stream package generated.
-v
Print verbose information about the stream package
generated. This information includes a per-second report of how much data has
been sent.
The format of the stream is committed. You will be able to receive your streams
on future versions of ZFS.Generate a send stream, which may be of a filesystem, and
may be incremental from a bookmark. If the destination is a filesystem or
volume, the pool must be read-only, or the filesystem must not be mounted.
When the stream generated from a filesystem or volume is received, the default
snapshot name will be "--head--".
-i snapshot|bookmark
zfs receive [-vnFu]
filesystem|volume|snapshot
Generate an incremental send stream. The incremental
source must be an earlier snapshot in the destination's history. It will
commonly be an earlier snapshot in the destination's filesystem, in which case
it can be specified as the last component of the name (the # or
@ character and following).
If the incremental target is a clone, the incremental source can be the origin
snapshot, or an earlier snapshot in the origin's filesystem, or the origin's
origin, etc.
-L
Generate a stream which may contain blocks larger than
128KB. This flag has no effect if the large_blocks pool feature is
disabled, or if the recordsize property of this filesystem has never been set
above 128KB. The receiving system must have the large_blocks pool
feature enabled as well. See zpool-features(5) for details on ZFS
feature flags and the large_blocks feature.
-e
Generate a more compact stream by using WRITE_EMBEDDED
records for blocks which are stored more compactly on disk by the
embedded_data pool feature. This flag has no effect if the
embedded_data feature is disabled. The receiving system must have the
embedded_data feature enabled. If the lz4_compress feature is
active on the sending system, then the receiving system must have that feature
enabled as well. See zpool-features(5) for details on ZFS feature flags
and the embedded_data feature.
Creates a snapshot whose contents are as specified in the
stream provided on standard input. If a full stream is received, then a new
file system is created as well. Streams are created using the zfs send
subcommand, which by default creates a full stream. zfs recv can be
used as an alias for zfs receive.
If an incremental stream is received, then the destination file system must
already exist, and its most recent snapshot must match the incremental
stream's source. For zvols, the destination device link is destroyed
and recreated, which means the zvol cannot be accessed during the
receive operation.
When a snapshot replication package stream that is generated by using the zfs
send -R command is received, any snapshots that do not exist on the
sending location are destroyed by using the zfs destroy -d
command.
The name of the snapshot (and file system, if a full stream is received) that
this subcommand creates depends on the argument type and the use of the
-d or -e options.
If the argument is a snapshot name, the specified snapshot is created. If
the argument is a file system or volume name, a snapshot with the same name as
the sent snapshot is created within the specified filesystem or
volume. If neither of the -d or -e options are specified,
the provided target snapshot name is used exactly as provided.
The -d and -e options cause the file system name of the target
snapshot to be determined by appending a portion of the sent snapshot's name
to the specified target filesystem. If the -d option is
specified, all but the first element of the sent snapshot's file system path
(usually the pool name) is used and any required intermediate file systems
within the specified one are created. If the -e option is specified,
then only the last element of the sent snapshot's file system name (i.e. the
name of the source file system itself) is used as the target file system name.
-d
zfs allow filesystem | volume
Discard the first element of the sent snapshot's file
system name, using the remaining elements to determine the name of the target
file system for the new snapshot as described in the paragraph above.
-e
Discard all but the last element of the sent snapshot's
file system name, using that element to determine the name of the target file
system for the new snapshot as described in the paragraph above.
-u
File system that is associated with the received stream
is not mounted.
-v
Print verbose information about the stream and the time
required to perform the receive operation.
-n
Do not actually receive the stream. This can be useful in
conjunction with the -v option to verify the name the receive operation
would use.
-F
Force a rollback of the file system to the most recent
snapshot before performing the receive operation. If receiving an incremental
replication stream (for example, one generated by zfs send -R -[iI]),
destroy snapshots and file systems that do not exist on the sending
side.
Displays permissions that have been delegated on the
specified filesystem or volume. See the other forms of zfs allow for
more information.
zfs allow [-ldug]
"everyone"|user|group[,...]
perm|@setname[,...] filesystem| volume
Delegates ZFS administration permission for the
file systems to non-privileged users.
[-ug] "everyone"|user|group[,...]
Permissions are generally the ability to use a ZFS subcommand or change a
ZFS property. The following permissions are available:
Specifies to whom the permissions are delegated. Multiple
entities can be specified as a comma-separated list. If neither of the
-ug options are specified, then the argument is interpreted
preferentially as the keyword "everyone", then as a user name, and
lastly as a group name. To specify a user or group named "everyone",
use the -u or -g options. To specify a group with the same name
as a user, use the -g options.
[-e] perm|@setname[,...]
Specifies that the permissions be delegated to
"everyone." Multiple permissions may be specified as a
comma-separated list. Permission names are the same as ZFS subcommand
and property names. See the property list below. Property set names, which
begin with an at sign ( @) , may be specified. See the -s form
below for details.
[-ld] filesystem|volume
Specifies where the permissions are delegated. If neither
of the -ld options are specified, or both are, then the permissions are
allowed for the file system or volume, and all of its descendents. If only the
-l option is used, then is allowed "locally" only for the
specified file system. If only the -d option is used, then is allowed
only for the descendent file systems.
NAME TYPE NOTES allow subcommand Must also have the permission that is being allowed clone subcommand Must also have the 'create' ability and 'mount' ability in the origin file system create subcommand Must also have the 'mount' ability destroy subcommand Must also have the 'mount' ability diff subcommand Allows lookup of paths within a dataset given an object number, and the ability to create snapshots necessary to 'zfs diff'. mount subcommand Allows mount/umount of ZFS datasets promote subcommand Must also have the 'mount' and 'promote' ability in the origin file system receive subcommand Must also have the 'mount' and 'create' ability rename subcommand Must also have the 'mount' and 'create' ability in the new parent rollback subcommand Must also have the 'mount' ability send subcommand share subcommand Allows sharing file systems over NFS or SMB protocols snapshot subcommand Must also have the 'mount' ability groupquota other Allows accessing any groupquota@... property groupused other Allows reading any groupused@... property userprop other Allows changing any user property userquota other Allows accessing any userquota@... property userused other Allows reading any userused@... property acltype property aclinherit property atime property canmount property casesensitivity property checksum property compression property copies property dedup property devices property exec property filesystem_limit property logbias property mlslabel property mountpoint property nbmand property normalization property primarycache property quota property readonly property recordsize property refquota property refreservation property reservation property secondarycache property setuid property shareiscsi property sharenfs property sharesmb property snapdir property snapshot_limit property utf8only property version property volblocksize property volsize property vscan property xattr property zoned property
zfs allow -c perm|@setname[,...] filesystem| volume
Sets "create time" permissions. These
permissions are granted (locally) to the creator of any newly-created
descendent file system.
zfs allow -s @setname
perm|@setname[,...] filesystem|volume
Defines or adds permissions to a permission set. The set
can be used by other zfs allow commands for the specified file system
and its descendents. Sets are evaluated dynamically, so changes to a set are
immediately reflected. Permission sets follow the same naming restrictions as
ZFS file systems, but the name must begin with an "at sign" (
@), and can be no more than 64 characters long.
zfs unallow [-rldug]
"everyone"|user| group[,...]
[perm|@setname[, ...]] filesystem|volume
Removes permissions that were granted with the zfs
allow command. No permissions are explicitly denied, so other permissions
granted are still in effect. For example, if the permission is granted by an
ancestor. If no permissions are specified, then all permissions for the
specified user, group, or everyone are removed.
Specifying "everyone" (or using the -e option) only removes
the permissions that were granted to "everyone", not all permissions
for every user and group. See the zfs allow command for a description
of the -ldugec options.
-r
zfs unallow [-r] -s @setname
[perm|@setname[,...]]
Recursively remove the permissions from this file system
and all descendents.
Removes permissions from a permission set. If no
permissions are specified, then all permissions are removed, thus removing the
set entirely.
zfs hold [-r] tag snapshot...
Adds a single reference, named with the tag
argument, to the specified snapshot or snapshots. Each snapshot has its own
tag namespace, and tags must be unique within that space.
If a hold exists on a snapshot, attempts to destroy that snapshot by using the
zfs destroy command return EBUSY.
-r
zfs holds [-r] snapshot...
Specifies that a hold with the given tag is applied
recursively to the snapshots of all descendent file systems.
Lists all existing user references for the given snapshot
or snapshots.
-r
zfs release [-r] tag snapshot...
Lists the holds that are set on the named descendent
snapshots, in addition to listing the holds on the named snapshot.
Removes a single reference, named with the tag
argument, from the specified snapshot or snapshots. The tag must already exist
for each snapshot.
If a hold exists on a snapshot, attempts to destroy that snapshot by using the
zfs destroy command return EBUSY.
-r
zfs diff [-FHt] snapshot snapshot|filesystem
Recursively releases a hold with the given tag on the
snapshots of all descendent file systems.
Display the difference between a snapshot of a given
filesystem and another snapshot of that filesystem from a later time or the
current contents of the filesystem. The first column is a character indicating
the type of change, the other columns indicate pathname, new pathname (in case
of rename), change in link count, and optionally file type and/or change time.
The types of change are:
-F
- The path has been removed + The path has been created M The path has been modified R The path has been renamed
-F
Display an indication of the type of file, in a manner
similar to the -F option of ls(1).
-H
B Block device C Character device / Directory > Door | Named pipe @ Symbolic link P Event port = Socket F Regular file
Give more parsable tab-separated output, without header
lines and without arrows.
-t
Display the path's inode change time as the first column
of output.
EXAMPLES¶
Example 1 Creating a ZFS File System Hierarchy The following commands create a file system named pool/home and a file system named pool/home/bob. The mount point /export/home is set for the parent file system, and is automatically inherited by the child file system.# zfs create pool/home # zfs set mountpoint=/export/home pool/home # zfs create pool/home/bob
Example 2 Creating a ZFS Snapshot The following command creates a snapshot named yesterday. This snapshot is mounted on demand in the .zfs/snapshot directory at the root of the pool/home/bob file system.
# zfs snapshot pool/home/bob@yesterday
Example 3 Creating and Destroying Multiple Snapshots The following command creates snapshots named yesterday of pool/home and all of its descendent file systems. Each snapshot is mounted on demand in the .zfs/snapshot directory at the root of its file system. The second command destroys the newly created snapshots.
# zfs snapshot -r pool/home@yesterday # zfs destroy -r pool/home@yesterday
Example 4 Disabling and Enabling File System Compression The following command disables the compression property for all file systems under pool/home. The next command explicitly enables compression for pool/home/anne.
# zfs set compression=off pool/home # zfs set compression=on pool/home/anne
Example 5 Listing ZFS Datasets The following command lists all active file systems and volumes in the system. Snapshots are displayed if the listsnaps property is on. The default is off. See zpool(8) for more information on pool properties.
# zfs list NAME USED AVAIL REFER MOUNTPOINT pool 450K 457G 18K /pool pool/home 315K 457G 21K /export/home pool/home/anne 18K 457G 18K /export/home/anne pool/home/bob 276K 457G 276K /export/home/bob
Example 6 Setting a Quota on a ZFS File System The following command sets a quota of 50 Gbytes for pool/home/bob.
# zfs set quota=50G pool/home/bob
Example 7 Listing ZFS Properties The following command lists all properties for pool/home/bob.
# zfs get all pool/home/bob NAME PROPERTY VALUE SOURCE pool/home/bob type filesystem - pool/home/bob creation Tue Jul 21 15:53 2009 - pool/home/bob used 21K - pool/home/bob available 20.0G - pool/home/bob referenced 21K - pool/home/bob compressratio 1.00x - pool/home/bob mounted yes - pool/home/bob quota 20G local pool/home/bob reservation none default pool/home/bob recordsize 128K default pool/home/bob mountpoint /pool/home/bob default pool/home/bob sharenfs off default pool/home/bob checksum on default pool/home/bob compression on local pool/home/bob atime on default pool/home/bob devices on default pool/home/bob exec on default pool/home/bob setuid on default pool/home/bob readonly off default pool/home/bob zoned off default pool/home/bob snapdir hidden default pool/home/bob acltype off default pool/home/bob aclinherit restricted default pool/home/bob canmount on default pool/home/bob shareiscsi off default pool/home/bob xattr on default pool/home/bob copies 1 default pool/home/bob version 4 - pool/home/bob utf8only off - pool/home/bob normalization none - pool/home/bob casesensitivity sensitive - pool/home/bob vscan off default pool/home/bob nbmand off default pool/home/bob sharesmb off default pool/home/bob refquota none default pool/home/bob refreservation none default pool/home/bob primarycache all default pool/home/bob secondarycache all default pool/home/bob usedbysnapshots 0 - pool/home/bob usedbydataset 21K - pool/home/bob usedbychildren 0 - pool/home/bob usedbyrefreservation 0 - pool/home/bob logbias latency default pool/home/bob dedup off default pool/home/bob mlslabel none default pool/home/bob relatime off default
The following command gets a single property value.
# zfs get -H -o value compression pool/home/bob on
The following command lists all properties with local settings for pool/home/bob.
# zfs get -r -s local -o name,property,value all pool/home/bob NAME PROPERTY VALUE pool/home/bob quota 20G pool/home/bob compression on
Example 8 Rolling Back a ZFS File System The following command reverts the contents of pool/home/anne to the snapshot named yesterday, deleting all intermediate snapshots.
# zfs rollback -r pool/home/anne@yesterday
Example 9 Creating a ZFS Clone The following command creates a writable file system whose initial contents are the same as pool/home/bob@yesterday.
# zfs clone pool/home/bob@yesterday pool/clone
Example 10 Promoting a ZFS Clone The following commands illustrate how to test out changes to a file system, and then replace the original file system with the changed one, using clones, clone promotion, and renaming:
# zfs create pool/project/production populate /pool/project/production with data # zfs snapshot pool/project/production@today # zfs clone pool/project/production@today pool/project/beta make changes to /pool/project/beta and test them # zfs promote pool/project/beta # zfs rename pool/project/production pool/project/legacy # zfs rename pool/project/beta pool/project/production once the legacy version is no longer needed, it can be destroyed # zfs destroy pool/project/legacy
Example 11 Inheriting ZFS Properties The following command causes pool/home/bob and pool/home/anne to inherit the checksum property from their parent.
# zfs inherit checksum pool/home/bob pool/home/anne
The following command causes pool/home/bob to revert to the received value for the quota property if it exists.
# zfs inherit -S quota pool/home/bob
Example 12 Remotely Replicating ZFS Data The following commands send a full stream and then an incremental stream to a remote machine, restoring them into poolB/received/fs@aand poolB/received/fs@b, respectively. poolB must contain the file system poolB/received, and must not initially contain poolB/received/fs.
# zfs send pool/fs@a | \ ssh host zfs receive poolB/received/fs@a # zfs send -i a pool/fs@b | ssh host \ zfs receive poolB/received/fs
Example 13 Using the zfs receive -d Option The following command sends a full stream of poolA/fsA/fsB@snap to a remote machine, receiving it into poolB/received/fsA/fsB@snap. The fsA/fsB@snap portion of the received snapshot's name is determined from the name of the sent snapshot. poolB must contain the file system poolB/received. If poolB/received/fsA does not exist, it is created as an empty file system.
# zfs send poolA/fsA/fsB@snap | \ ssh host zfs receive -d poolB/received
Example 14 Setting User Properties The following example sets the user-defined com.example:department property for a dataset.
# zfs set com.example:department=12345 tank/accounting
Example 15 Creating a ZFS Volume as an iSCSI Target Device The following example shows how to create a ZFS volume as an iSCSI target.
# zfs create -V 2g pool/volumes/vol1 # zfs set shareiscsi=on pool/volumes/vol1 # iscsitadm list target Target: pool/volumes/vol1 iSCSI Name: iqn.1986-03.com.sun:02:7b4b02a6-3277-eb1b-e686-a24762c52a8c Connections: 0
After the iSCSI target is created, set up the iSCSI initiator. For more information about the Solaris iSCSI initiator, see iscsitadm(1M). Example 16 Performing a Rolling Snapshot The following example shows how to maintain a history of snapshots with a consistent naming scheme. To keep a week's worth of snapshots, the user destroys the oldest snapshot, renames the remaining snapshots, and then creates a new snapshot, as follows:
# zfs destroy -r pool/users@7daysago # zfs rename -r pool/users@6daysago @7daysago # zfs rename -r pool/users@5daysago @6daysago # zfs rename -r pool/users@4daysago @5daysago # zfs rename -r pool/users@3daysago @4daysago # zfs rename -r pool/users@2daysago @3daysago # zfs rename -r pool/users@yesterday @2daysago # zfs rename -r pool/users@today @yesterday # zfs snapshot -r pool/users@today
Example 17 Setting sharenfs Property Options on a ZFS File System The following commands show how to set sharenfs property options to enable rw access for a set of IP addresses and to enable root access for system neo on the tank/home file system.
# zfs set sharenfs='rw=@123.123.0.0/16,root=neo' tank/home
If you are using DNS for host name resolution, specify the fully qualified hostname. Example 18 Delegating ZFS Administration Permissions on a ZFS Dataset The following example shows how to set permissions so that user cindys can create, destroy, mount, and take snapshots on tank/cindys. The permissions on tank/cindys are also displayed.
# zfs allow cindys create,destroy,mount,snapshot tank/cindys # zfs allow tank/cindys ------------------------------------------------------------- Local+Descendent permissions on (tank/cindys) user cindys create,destroy,mount,snapshot -------------------------------------------------------------
Because the tank/cindys mount point permission is set to 755 by default, user cindys will be unable to mount file systems under tank/cindys. Set an ACL similar to the following syntax to provide mount point access:
# chmod A+user:cindys:add_subdirectory:allow /tank/cindys
Example 19 Delegating Create Time Permissions on a ZFS Dataset The following example shows how to grant anyone in the group staff to create file systems in tank/users. This syntax also allows staff members to destroy their own file systems, but not destroy anyone else's file system. The permissions on tank/users are also displayed.
# zfs allow staff create,mount tank/users # zfs allow -c destroy tank/users # zfs allow tank/users ------------------------------------------------------------- Create time permissions on (tank/users) create,destroy Local+Descendent permissions on (tank/users) group staff create,mount -------------------------------------------------------------
Example 20 Defining and Granting a Permission Set on a ZFS Dataset The following example shows how to define and grant a permission set on the tank/users file system. The permissions on tank/users are also displayed.
# zfs allow -s @pset create,destroy,snapshot,mount tank/users # zfs allow staff @pset tank/users # zfs allow tank/users ------------------------------------------------------------- Permission sets on (tank/users) @pset create,destroy,mount,snapshot Create time permissions on (tank/users) create,destroy Local+Descendent permissions on (tank/users) group staff @pset,create,mount -------------------------------------------------------------
Example 21 Delegating Property Permissions on a ZFS Dataset The following example shows to grant the ability to set quotas and reservations on the users/home file system. The permissions on users/home are also displayed.
# zfs allow cindys quota,reservation users/home # zfs allow users/home ------------------------------------------------------------- Local+Descendent permissions on (users/home) user cindys quota,reservation ------------------------------------------------------------- cindys% zfs set quota=10G users/home/marks cindys% zfs get quota users/home/marks NAME PROPERTY VALUE SOURCE users/home/marks quota 10G local
Example 22 Removing ZFS Delegated Permissions on a ZFS Dataset The following example shows how to remove the snapshot permission from the staff group on the tank/users file system. The permissions on tank/users are also displayed.
# zfs unallow staff snapshot tank/users # zfs allow tank/users ------------------------------------------------------------- Permission sets on (tank/users) @pset create,destroy,mount,snapshot Create time permissions on (tank/users) create,destroy Local+Descendent permissions on (tank/users) group staff @pset,create,mount -------------------------------------------------------------
Example 23 Showing the differences between a snapshot and a ZFS Dataset The following example shows how to see what has changed between a prior snapshot of a ZFS Dataset and its current state. The -F option is used to indicate type information for the files affected.
# zfs diff -F tank/test@before tank/test M / /tank/test/ M F /tank/test/linked (+1) R F /tank/test/oldname -> /tank/test/newname - F /tank/test/deleted + F /tank/test/created M F /tank/test/modified
Example 24 Creating a bookmark The following example create a bookmark to a snapshot. This bookmark can then be used instead of snapshot in send streams.
# zfs bookmark rpool@snapshot rpool#bookmark
ENVIRONMENT VARIABLES¶
- ZFS_ABORT
- Cause zfs to dump core on exit for the purposes of running ::findleaks.
EXIT STATUS¶
The following exit values are returned: 0Successful completion.
1
An error occurred.
2
Invalid command line options were specified.
SEE ALSO¶
chmod(2), fsync(2), gzip(1), mount(8), ssh(1), stat(2), write(2), zpool(8)November 19, 2013 | ZFS pool 28, filesystem 5 |