xfs_admin(8) System Manager's Manual xfs_admin(8)
NAME
xfs_admin - change parameters of an XFS filesystem
SYNOPSIS
xfs_admin [ -eflpu ] [ -c 0|1 ] [ -L label ] [ -U uuid ] device [
logdev ]
xfs_admin -V
DESCRIPTION
xfs_admin uses the xfs_db(8) command to modify various parameters of a
filesystem.
Devices that are mounted cannot be modified. Administrators must un-
mount filesystems before xfs_admin or xfs_db(8) can convert parameters.
A number of parameters of a mounted filesystem can be examined and mod-
ified 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.
OPTIONS
-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 IDenti-
fier).
-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. In-
stead, enough information is kept in other parts of the filesys-
tem 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 charac-
ters, 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 incompati-
ble 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.
SEE ALSO
mkfs.xfs(8), mount(8), xfs_db(8), xfs_growfs(8), xfs_repair(8), xfs(5).
xfs_admin(8)