3.5.3. Synchronizing Quotas

3.5.3. Synchronizing Quotas

GFS stores all quota information in its own internal file on disk. A GFS node does not update this quota file for every file system write; rather, it updates the quota file once every 60 seconds. This is necessary to avoid contention among nodes writing to the quota file, which would cause a slowdown in performance.

As a user or group approaches their quota limit, GFS dynamically reduces the time between its quota-file updates to prevent the limit from being exceeded. The normal time period between quota synchronizations is a tunable parameter, quota_quantum, and can be changed using the gfs_tool command. By default, the time period is 60 seconds. Also, the quota_quantum parameter must be set on each node and each time the file system is mounted. (Changes to the quota_quantum parameter are not persistent across unmounts.)

To see the current values of the GFS tunable parameters, including quota_quantum, you can use the gfs_tool gettune, as described in Section 3.4, “Displaying GFS Tunable Parameters”.

You can use the gfs_quota sync command to synchronize the quota information from a node to the on-disk quota file between the automatic updates performed by GFS.

Usage

Synchronizing Quota Information

gfs_quota sync -f MountPoint
MountPoint

Specifies the GFS file system to which the actions apply.

Tuning the Time Between Synchronizations

gfs_tool settune MountPoint quota_quantum Seconds
MountPoint

Specifies the GFS file system to which the actions apply.

Seconds

Specifies the new time period between regular quota-file synchronizations by GFS. Smaller values may increase contention and slow down performance.

Examples

This example synchronizes the quota information from the node it is run on to file system /gfs.

gfs_quota sync -f /gfs

This example changes the default time period between regular quota-file updates to one hour (3600 seconds) for file system /gfs on a single node.

gfs_tool settune /gfs quota_quantum 3600

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