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  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.

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 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,
              recovery procedures (e.g. reformat followed by restoration from backup; or  running
              xfs_repair 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.

       -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)