man > xfs_admin(8)

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 ] de‐
       vice [ 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 unmount filesystems  before
       xfs_admin  or xfs_db(8) can convert parameters.  A number of parameters of a mounted filesys‐
       tem can be examined and modified using the xfs_growfs(8) command.

       The optional logdev parameter specifies the device special file where the filesystem's exter‐
       nal 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 en‐
              abled (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 de‐
              vice (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 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).

              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. 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.

       -O feature1=status,feature2=status...
              Add or remove features on an existing V5 filesystem.  The features should be specified
              as a comma-separated list.  status should be either 0 to disable the feature or  1  to
              enable the feature.  Note, however, that most features cannot be disabled.

              NOTE:  Administrators  must ensure the filesystem is clean by running xfs_repair -n to
              inspect the filesystem before performing the upgrade.  If corruption is found,  recov‐
              ery  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 downgraded after this feature is enabled.  Once enabled, the filesystem
                  will not be writable by older kernels.  This feature 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 counters. 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 en‐
                  abled. Once enabled, the filesystem will not be mountable by older kernels.   This
                  feature was added to Linux 5.19.

       -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.

       -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)