xfs_admin(8) System Manager's Manual xfs_admin(8)
NAME
xfs_admin - change parameters of an XFS filesystem
SYNOPSIS
xfs_admin [ -eflpu ] [ -O featurelist ] [ -c 0|1 ] [ -L label ] [ -U
uuid ] [ -r rtdev ] 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 modi-
fied 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).
This option only applies to the deprecated V4 format.
-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).
This option only applies to the deprecated V4 format.
-l Print the current filesystem label.
-p Enable 32bit project identifier support (PROJID32BIT feature).
This option only applies to the deprecated V4 format.
-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).
In other words, this option only applies to the deprecated V4
format.
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.
-O feature1=status,feature2=status...
Add or remove features on an existing V5 filesystem. The fea-
tures should be specified as a comma-separated list. status
should be either 0 to disable the feature or 1 to enable the fea-
ture. Note, however, that most features cannot be disabled.
NOTE: Administrators must ensure the filesystem is clean by run-
ning xfs_repair -n to inspect the filesystem before performing
the upgrade. If corruption is found, recovery procedures (e.g.
reformat followed by restoration from backup; or running xfs_re-
pair without the -n) must be followed to clean the filesystem.
Supported features are as follows:
inobtcount
Keep a count the number of blocks in each inode btree in the
AGI. This reduces mount time by speeding up metadata space
reservation calculations. The filesystem cannot be down-
graded after this feature is enabled. Once enabled, the
filesystem will not be writable by older kernels. This fea-
ture was added to Linux 5.10.
bigtime
Upgrade a filesystem to support larger timestamps up to the
year 2486. The filesystem cannot be downgraded after this
feature is enabled. Once enabled, the filesystem will not be
mountable by older kernels. This feature was added to Linux
5.10.
nrext64
Upgrade a filesystem to support large per-inode extent coun-
ters. The maximum data fork extent count will be 2^48 - 1,
while the maximum attribute fork extent count will be 2^32 -
1. The filesystem cannot be downgraded after this feature is
enabled. Once enabled, the filesystem will not be mountable
by older kernels. This feature was added to Linux 5.19.
exchange
Upgrade a filesystem to support atomic file content exchanges
through the XFS_IOC_EXCHANGE_RANGE ioctl, and to support on-
line repairs of directories, extended attributes, symbolic
links, and realtime free space metadata. The filesystem can-
not be downgraded after this feature is enabled. Once en-
abled, the filesystem will not be mountable by older kernels.
-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 re-
store, which will restore the original UUID and remove the incom-
patible feature flag as needed.
-r rtdev
Specifies the device special file where the filesystem's realtime
section resides. Only for those filesystems which use a realtime
section.
-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)
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