9.3. XFS Quota Management
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:
-
uquota/uqnoenforce - User quotas
-
gquota/gqnoenforce - Group quotas
-
pquota/pqnoenforce - Project quota
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:
- quota
username/userID
-
Show usage and limits for the given usernameuserID
- df
-
Shows free and used counts for blocks and inodes.
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:
- report
/path
-
Reports quota information for a specific file system.
- limit
-
Modify quota limits.
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
While real-time blocks (rtbhard/rtbsoft) are described in man xfs_quota as valid units when setting quotas, the real-time sub-volume is not enabled in this release. As such, the rtbhard and rtbsoft options are not applicable.
Before configuring limits for project-controlled directories, add them first to /etc/projects. Project names can be added to/etc/projectid to map project IDs to project names. Once a project is added to /etc/projects, initialize its project directory using the following command:
xfs_quota -c 'project -s projectname'
Quotas for projects with initialized directories can then be configured, as in:
xfs_quota -x -c 'limit -p bsoft=1000m bhard=1200m projectname'
Generic quota configuration tools (e.g. quota, repquota, edquota) may also be used to manipulate XFS quotas. However, these tools cannot be used with XFS project quotas.
For more information about setting XFS quotas, refer to man xfs_quota.
