xfs_admin - change parameters of an XFS filesystem
xfs_admin [ -eflpu ] [ -c 0|1 ] [
-L label ] [ -U uuid ] device [
logdev ]
xfs_admin -V
xfs_admin uses the xfs_db(8) command to modify
various parameters of a filesystem.
Devices that are mounted cannot be modified. Administrators must
unmount filesystems before xfs_admin or xfs_db(8) can convert
parameters. A number of parameters of a mounted filesystem can be examined
and modified using the xfs_growfs(8) command.
The optional logdev parameter specifies the device special
file where the filesystem's external log resides. This is required only for
filesystems that use an external log. See the mkfs.xfs -l option, and
refer to xfs(5) for a detailed description of the XFS log.
- -e
- Enables unwritten extent support on a filesystem that does not already
have this enabled (for legacy filesystems, it can't be disabled anymore at
mkfs time).
- -f
- Specifies that the filesystem image to be processed is stored in a regular
file at device (see the mkfs.xfs -d file
option).
- -j
- Enables version 2 log format (journal format supporting larger log
buffers).
- -l
- Print the current filesystem label.
- -p
- Enable 32bit project identifier support (PROJID32BIT feature).
- -u
- Print the current filesystem UUID (Universally Unique IDentifier).
- -c 0|1
- Enable (1) or disable (0) lazy-counters in the filesystem.
- Lazy-counters may not be disabled on Version 5 superblock filesystems
(i.e. those with metadata CRCs enabled).
- This operation may take quite a bit of time on large filesystems as the
entire filesystem needs to be scanned when this option is changed.
- With lazy-counters enabled, the superblock is not modified or logged on
every change of the free-space and inode counters. Instead, enough
information is kept in other parts of the filesystem to be able to
maintain the counter values without needing to keep them in the
superblock. This gives significant improvements in performance on some
configurations and metadata intensive workloads.
- -L label
- Set the filesystem label to label. XFS filesystem labels can be at
most 12 characters long; if label is longer than 12 characters,
xfs_admin will truncate it and print a warning message. The
filesystem label can be cleared using the special "--"
value for label.
- -U uuid
- Set the UUID of the filesystem to uuid. A sample UUID looks like
this: "c1b9d5a2-f162-11cf-9ece-0020afc76f16". The uuid
may also be nil, which will set the filesystem UUID to the null
UUID. The uuid may also be generate, which will generate a
new UUID for the filesystem. Note that on CRC-enabled filesystems, this
will set an incompatible flag such that older kernels will not be able to
mount the filesystem. To remove this incompatible flag, use
restore, which will restore the original UUID and remove the
incompatible feature flag as needed.
- -V
- Prints the version number and exits.
The mount(8) manual entry describes how to mount a
filesystem using its label or UUID, rather than its block special device
name.