The XFS quota subsystem manages limits on disk space (blocks) and file (inode) usage. XFS quotas control and/or report on usage of these items on a user, group, or directory/project level. Also, note that while user, group, and directory/project quotas are enabled independently, group and project quotas a mutually exclusive.

When managing on a per-directory or per-project basis, XFS manages the disk usage of directory heirarchies associated with a specific project. In doing so, XFS recognizes cross-organizational "group" boundaries between projects. This provides a level of control that is broader than what is available when managing quotas for users or groups.

XFS quotas are enabled at mount time, with specific mount options. Each mount option can also be specified as noenforce; this will allow usage reporting without enforcing any limits. Valid quota mount options are:

Once quotas are enabled, the xfs_quota tool can be used to set limits and report on disk usage. By default, xfs_quota is run interactively, and in basic mode. Basic mode sub-commands simply report usage, and are available to all users. Basic xfs_quota sub-commands include:

In contrast, xfs_quota also has an expert mode. The sub-commands of this mode allow actual configuration of limits, and are available only to users with elevated privileges. To use expert mode sub-commands interactively, run xfs_quota -x. Expert mode sub-commands include:

For a complete list of sub-commands for either basic or expert mode, use the sub-command help.

All sub-commands can also be run directly from a command line using the -c option, with -x for expert sub-commands. For example, to display a sample quota report for /home (on /dev/blockdevice), use the command xfs_quota -cx 'report -h' /home. This will display output similar to the following:

User quota on /home (/dev/blockdevice)
                        Blocks              
User ID      Used   Soft   Hard Warn/Grace   
---------- --------------------------------- 
root            0      0      0  00 [------]
testuser   103.4G      0      0  00 [------]
...

To set a soft and hard inode count limit of 500 and 700 respectively for user john (whose home directory is /home/john), use the following command:

xfs_quota -x -c 'limit isoft=500 ihard=700 /home/john'

By default, the limit sub-command recognizes targets as users. When configuring the limits for a group, use the -g option (as in the previous example). Similarly, use -p for projects.

Soft and hard block limits can also be configured using bsoft/bhard instead of isoft/ihard. For example, to set a soft and hard block limit of 1000m and 1200m, respectively, to group accounting on the /target/path file system, use the following command:

xfs_quota -x -c 'limit -g bsoft=1000m bhard=1200m accounting' /target/path