NAME¶
mount.gfs2 - GFS2 mount options
SYNOPSIS¶
mount -a [-fnrsvw] -t gfs2 [-O options]
mount [-fnrsvw] -t gfs2 [-o options ]
device dir
DESCRIPTION¶
For details on the common mount options, please see the
mount(8) command
man page. The
device may be any block device on which you have created
a GFS2 filesystem. Examples include a single disk partition (e.g. /dev/sdb3),
a loopback device, a device exported from another node (e.g. an iSCSI device),
or a logical volume (typically comprised of a number of individual disks).
device does not necessarily need to match the device name as seen on
another node in the cluster, nor does it need to be a logical volume. However,
the use of a cluster-aware volume manager such as CLVM2 (see
lvm(8))
will guarantee that the managed devices are named identically on each node in
a cluster (for much easier management), and will allow you to configure a very
large volume from multiple storage units (e.g. disk drives).
device must make the entire filesystem storage area visible to the
computer. That is, you cannot mount different parts of a single filesystem on
different computers. Each computer must see an entire filesystem. You may,
however, mount several GFS2 filesystems if you want to distribute your data
storage in a controllable way.
This man page describes GFS2-specific options that can be passed to the GFS2
file system at mount time, using the
-o flag. There are many other
-o options handled by the generic mount command
mount(8).
However, the options described below are specifically for GFS2, and are not
interpreted by the mount command nor by the kernel's Virtual File System. GFS2
and non-GFS2 options may be intermingled after the
-o, separated by
commas (but no spaces).
The options commit, discard, errors, quota_quantum, statfs_quantum,
statfs_percent, barrier, acl, quota, suiddir, and data can be changed after
mount using the "mount -o remount,option /mountpoint" command. The
options quota, discard, barrier, acl, and suiddir support the "no"
prefix. For example, "noacl" turns off what "acl" turns
on.
If you have trouble mounting GFS2, check the syslog (e.g. /var/log/messages) for
specific error messages.
OPTIONS¶
- lockproto=LockProtoName
- This specifies which inter-node lock protocol is used by
the GFS2 filesystem for this mount, overriding the default lock protocol
name stored in the filesystem's on-disk superblock.
The LockProtoName must be one of the supported locking protocols,
currently these are lock_nolock and lock_dlm.
The default lock protocol name is written to disk initially when creating
the filesystem with mkfs.gfs2(8), -p option. It can be changed
on-disk by using the gfs2_tool(8) utility's sb proto
command.
The lockproto mount option should be used only under special
circumstances in which you want to temporarily use a different lock
protocol without changing the on-disk default. Using the incorrect lock
protocol on a cluster filesystem mounted from more than one node will
almost certainly result in filesystem corruption.
- locktable=LockTableName
- This specifies the identity of the cluster and of the
filesystem for this mount, overriding the default cluster/filesystem
identify stored in the filesystem's on-disk superblock. The
cluster/filesystem name is recognized globally throughout the cluster, and
establishes a unique namespace for the inter-node locking system, enabling
the mounting of multiple GFS2 filesystems.
The format of LockTableName is lock-module-specific. For
lock_dlm, the format is clustername:fsname. For
lock_nolock, the field is ignored.
The default cluster/filesystem name is written to disk initially when
creating the filesystem with mkfs.gfs2(8), -t option. It can be
changed on-disk by using the gfs2_tool(8) utility's sb table
command.
The locktable mount option should be used only under special
circumstances in which you want to mount the filesystem in a different
cluster, or mount it as a different filesystem name, without changing the
on-disk default.
- localcaching
- This flag tells GFS2 that it is running as a local (not
clustered) filesystem, so it can turn on some block caching optimizations
that can't be used when running in cluster mode.
This is turned on automatically by the lock_nolock module, but can be
overridden by using the ignore_local_fs option.
- localflocks
- This flag tells GFS2 that it is running as a local (not
clustered) filesystem, so it can allow the kernel VFS layer to do all
flock and fcntl file locking. When running in cluster mode, these file
locks require inter-node locks, and require the support of GFS2. When
running locally, better performance is achieved by letting VFS handle the
whole job.
This is turned on automatically by the lock_nolock module, but can be
overridden by using the ignore_local_fs option.
- errors=[panic|withdraw]
- Setting errors=panic causes GFS2 to oops when encountering
an error that would otherwise cause the mount to withdraw or print an
assertion warning. The default setting is errors=withdraw. This option
should not be used in a production system. It replaces the earlier
debug option on kernel versions 2.6.31 and above.
- ignore_local_fs
- By default, using the nolock lock module automatically
turns on the localcaching and localflocks optimizations.
ignore_local_fs forces GFS2 to treat the filesystem as if it were a
multihost (clustered) filesystem, with localcaching and
localflocks optimizations turned off.
- upgrade
- This flag tells GFS2 to upgrade the filesystem's on-disk
format to the version supported by the current GFS2 software installation
on this computer. If you try to mount an old-version disk image, GFS2 will
notify you via a syslog message that you need to upgrade. Try mounting
again, using the -o upgrade option. When upgrading, only one node
may mount the GFS2 filesystem.
- acl
- Enables POSIX Access Control List acl(5) support
within GFS2.
- spectator
- Mount this filesystem using a special form of read-only
mount. The mount does not use one of the filesystem's journals. The node
is unable to recover journals for other nodes.
- suiddir
- Sets owner of any newly created file or directory to be
that of parent directory, if parent directory has S_ISUID permission
attribute bit set. Sets S_ISUID in any new directory, if its parent
directory's S_ISUID is set. Strips all execution bits on a new file, if
parent directory owner is different from owner of process creating the
file. Set this option only if you know why you are setting it.
- quota=[off/account/on]
- Turns quotas on or off for a filesystem. Setting the quotas
to be in the "account" state causes the per UID/GID usage
statistics to be correctly maintained by the filesystem, limit and warn
values are ignored. The default value is "off".
- discard
- Causes GFS2 to generate "discard" I/O requests
for blocks which have been freed. These can be used by suitable hardware
to implement thin-provisioning and similar schemes. This feature is
supported in kernel version 2.6.30 and above.
- barrier
- This option, which defaults to on, causes GFS2 to send I/O
barriers when flushing the journal. The option is automatically turned off
if the underlying device does not support I/O barriers. We highly
recommend the use of I/O barriers with GFS2 at all times unless the block
device is designed so that it cannot lose its write cache content (e.g.
its on a UPS, or it doesn't have a write cache)
- commit=secs
- This is similar to the ext3 commit= option in that
it sets the maximum number of seconds between journal commits if there is
dirty data in the journal. The default is 60 seconds. This option is only
provided in kernel versions 2.6.31 and above.
- data=[ordered|writeback]
- When data=ordered is set, the user data modified by a
transaction is flushed to the disk before the transaction is committed to
disk. This should prevent the user from seeing uninitialized blocks in a
file after a crash. Data=writeback mode writes the user data to the disk
at any time after it's dirtied. This doesn't provide the same consistency
guarantee as ordered mode, but it should be slightly faster for some
workloads. The default is ordered mode.
- meta
- This option results in selecting the meta filesystem root
rather than the normal filesystem root. This option is normally only used
by the GFS2 utility functions. Altering any file on the GFS2 meta
filesystem may render the filesystem unusable, so only experts in the GFS2
on-disk layout should use this option.
- quota_quantum=secs
- This sets the number of seconds for which a change in the
quota information may sit on one node before being written to the quota
file. This is the preferred way to set this parameter. The value is an
integer number of seconds greater than zero. The default is 60 seconds.
Shorter settings result in faster updates of the lazy quota information
and less likelihood of someone exceeding their quota. Longer settings make
filesystem operations involving quotas faster and more efficient.
- statfs_quantum=secs
- Setting statfs_quantum to 0 is the preferred way to set the
slow version of statfs. The default value is 30 secs which sets the
maximum time period before statfs changes will be syned to the master
statfs file. This can be adjusted to allow for faster, less accurate
statfs values or slower more accurate values. When set to 0, statfs will
always report the true values.
- statfs_percent=value
- This setting provides a bound on the maximum percentage
change in the statfs information on a local basis before it is synced back
to the master statfs file, even if the time period has not expired. If the
setting of statfs_quantum is 0, then this setting is ignored.
BUGS¶
GFS2 doesn't support
errors=remount-ro or
data=journal. It is not possible to switch support for user and
group quotas on and off independently of each other. Some of the error
messages are rather cryptic, if you encounter one of these messages check
firstly that gfs_controld is running and secondly that you have enough
journals on the filesystem for the number of nodes in use.
SEE ALSO¶
gfs2(8),
mount(8) for general mount options,
chmod(1) and
chmod(2) for access permission flags,
acl(5) for access control
lists,
lvm(8) for volume management,
ccs(7) for cluster
management,
umount(8),
initrd(4).