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VFS_SHADOW_COPY2(8) | System Administration tools | VFS_SHADOW_COPY2(8) |
NAME¶
vfs_shadow_copy2 - Expose snapshots to Windows clients as shadow copies.SYNOPSIS¶
vfs objects = shadow_copy2
DESCRIPTION¶
This VFS module is part of the samba(7) suite. The vfs_shadow_copy2 VFS module offers a functionality similar to Microsoft Shadow Copy services. When set up properly, this module allows Microsoft Shadow Copy clients to browse through file system snapshots as "shadow copies" on Samba shares. This is a second implementation of a shadow copy module which has the following additional features (compared to the original shadow_copy(8) module): 1.There is no need any more to populate your share's
root directory with symlinks to the snapshots if the file system stores the
snapshots elsewhere. Instead, you can flexibly configure the module where to
look for the file system snapshots. This can be very important when you have
thousands of shares, or use [homes].
2.Snapshot directories need not be in one fixed central
place but can be located anywhere in the directory tree. This mode helps to
support file systems that offer snapshotting of particular subtrees, for
example the GPFS independent file sets.
3.Vanity naming for snapshots: snapshots can be named in
any format compatible with str[fp]time conversions.
4.Timestamps can be represented in localtime rather than
UTC.
5.The inode number of the files can optionally be
altered to be different from the original. This fixes the 'restore' button in
the Windows GUI to work without a sharing violation when serving from file
systems, like GPFS, that return the same device and inode number for the
snapshot file and the original.
6.Shadow copy results are by default sorted before being
sent to the client. This is beneficial for filesystems that don't read
directories alphabetically (the default unix). Sort ordering can be configured
and sorting can be turned off completely if the file system sorts its
directory listing.
This module is stackable.
CONFIGURATION¶
vfs_shadow_copy2 relies on a filesystem snapshot implementation. Many common filesystems have native support for this. Filesystem snapshots must be available under specially named directories in order to be recognized by vfs_shadow_copy2. These snapshot directory is typically a direct subdirectory of the share root's mountpoint but there are other modes that can be configured with the parameters described in detail below. The snapshot at a given point in time is expected in a subdirectory of the snapshot directory where the snapshot's directory is expected to be a formatted version of the snapshot time. The default format which can be changed with the shadow:format option is @GMT-YYYY.MM.DD-hh.mm.ss, where:•YYYY is the 4 digit year
•MM is the 2 digit month
•DD is the 2 digit day
•hh is the 2 digit hour
•mm is the 2 digit minute
•ss is the 2 digit second.
The vfs_shadow_copy2 snapshot naming convention can be produced with the
following date(1) command:
TZ=GMT date +@GMT-%Y.%m.%d-%H.%M.%S
OPTIONS¶
shadow:mountpoint = MOUNTPOINTWith this parameter, one can specify the mount point of
the filesystem that contains the share path. Usually this mount point is
automatically detected. But for some constellations, in particular tests, it
can be convenient to be able to specify it.
Example: shadow:mountpoint = /path/to/filesystem
Default: shadow:mountpoint = NOT SPECIFIED
shadow:snapdir = SNAPDIR
Path to the directory where the file system of the share
keeps its snapshots. If an absolute path is specified, it is used as-is. If a
relative path is specified, then it is taken relative to the mount point of
the filesystem of the share root. (See shadow:mountpoint.)
Note that shadow:snapdirseverywhere depends on this parameter and needs a
relative path. Setting an absolute path disables shadow:snapdirseverywhere.
Note that the shadow:crossmountpoints option also requires a relative snapdir.
Setting an absolute path disables shadow:crossmountpoints.
Example: shadow:snapdir = /some/absolute/path
Default: shadow:snapdir = .snapshots
shadow:basedir = BASEDIR
The basedir option allows to specify a directory between
the share's mount point and the share root, relative to which the file
system's snapshots are taken.
For example, if
then the snapshot of a file = mountpoint/rel_basedir/rel_share_root/rel_file at
a time TIME will be found under
snapshot_path/FS_GMT_TOKEN(TIME)/rel_share_root/rel_file, where
FS_GMT_TOKEN(TIME) is the timestamp string belonging to TIME in the format
required by the file system. (See shadow:format.)
The default for the basedir is the mount point of the file system of the share
root (see shadow:mountpoint).
Note that the shadow:snapdirseverywhere and shadow:crossmountpoints options are
incompatible with shadow:basedir and disable the basedir setting.
shadow:sort = asc/desc
•basedir = mountpoint/rel_basedir
•share_root = basedir/rel_share_root
•snapshot_path = mountpoint/snapdir
or snapshot_path = snapdir if snapdir is absolute
By default, this module sorts the shadow copy data
alphabetically before sending it to the client. With this parameter, one can
specify the sort order. Possible known values are desc (descending, the
default) and asc (ascending). If the file system lists directories
alphabetically sorted, one can turn off sorting in this module by specifying
any other value.
Example: shadow:sort = asc
Example: shadow:sort = none
Default: shadow:sort = desc
shadow:localtime = yes/no
This is an optional parameter that indicates whether the
snapshot names are in UTC/GMT or in local time. If it is disabled then UTC/GMT
is expected.
shadow:localtime = no
shadow:format = format specification for snapshot names
This is an optional parameter that specifies the format
specification for the naming of snapshots in the file system. The format must
be compatible with the conversion specifications recognized by str[fp]time.
Default: shadow:format = "@GMT-%Y.%m.%d-%H.%M.%S"
shadow:sscanf = yes/no
This paramter can be used to specify that the time in
format string is given as an unsigned long integer (%lu) rather than a time
strptime() can parse. The result must be a unix time_t time.
Default: shadow:sscanf = no
shadow:fixinodes = yes/no
If you enable shadow:fixinodes then this module will
modify the apparent inode number of files in the snapshot directories using a
hash of the files path. This is needed for snapshot systems where the
snapshots have the same device:inode number as the original files (such as
happens with GPFS snapshots). If you don't set this option then the 'restore'
button in the shadow copy UI will fail with a sharing violation.
Default: shadow:fixinodes = no
shadow:snapdirseverywhere = yes/no
If you enable shadow:snapdirseverywhere then this module
will look out for snapshot directories in the current working directory and
all parent directories, stopping at the mount point by default. But see
shadow:crossmountpoints how to change that behaviour.
An example where this is needed are independent filesets in IBM's GPFS, but
other filesystems might support snapshotting only particular subtrees of the
filesystem as well.
Note that shadow:snapdirseverywhere depends on shadow:snapdir and needs it to be
a relative path. Setting an absolute snapdir path disables
shadow:snapdirseverywhere.
Note that this option is incompatible with the shadow:basedir option and removes
the shadow:basedir setting by itself.
Example: shadow:snapdirseverywhere = yes
Default: shadow:snapdirseverywhere = no
shadow:crossmountpoints = yes/no
This option is effective in the case of
shadow:snapdirseverywhere = yes. Setting this option makes the module not stop
at the first mount point encountered when looking for snapdirs, but lets it
search potentially all through the path instead.
An example where this is needed are independent filesets in IBM's GPFS, but
other filesystems might support snapshotting only particular subtrees of the
filesystem as well.
Note that shadow:snapdirseverywhere depends on shadow:snapdir and needs it to be
a relative path. Setting an absolute snapdir path disables
shadow:snapdirseverywhere.
Note that this option is incompatible with the shadow:basedir option and removes
the shadow:basedir setting by itself.
Example: shadow:crossmountpoints = yes
Default: shadow:crossmountpoints = no
EXAMPLES¶
Add shadow copy support to user home directories:[homes] vfs objects = shadow_copy2 shadow:snapdir = /data/snapshots shadow:basedir = /data/home shadow:sort = desc
CAVEATS¶
This is not a backup, archival, or version control solution. With Samba or Windows servers, vfs_shadow_copy2 is designed to be an end-user tool only. It does not replace or enhance your backup and archival solutions and should in no way be considered as such. Additionally, if you need version control, implement a version control system.VERSION¶
This man page is correct for version 4.0 of the Samba suite.AUTHOR¶
The original Samba software and related utilities were created by Andrew Tridgell. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed.11/12/2017 | Samba 4.2 |