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.


Synchronizing Quota Information

gfs_quota sync -f MountPoint

Specifies the GFS file system to which the actions apply.

Tuning the Time Between Synchronizations

gfs_tool settune MountPoint quota_quantum Seconds

Specifies the GFS file system to which the actions apply.


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


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

Note: This documentation is provided {and copyrighted} by Red Hat®, Inc. and is released via the Open Publication License. The copyright holder has added the further requirement that Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder. The CentOS project redistributes these original works (in their unmodified form) as a reference for CentOS-5 because CentOS-5 is built from publicly available, open source SRPMS. The documentation is unmodified to be compliant with upstream distribution policy. Neither CentOS-5 nor the CentOS Project are in any way affiliated with or sponsored by Red Hat®, Inc.