Red Hat Training

A Red Hat training course is available for Red Hat Enterprise Linux

4.5.4. Synchronizing Quotas with the quotasync Command

GFS2 stores all quota information in its own internal file on disk. A GFS2 node does not update this quota file for every file system write; rather, by default 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, GFS2 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. You can change this from its default value of 60 seconds using the quota_quantum= mount option, as described in Table 4.2, “GFS2-Specific Mount Options”. 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. You can update the quota_quantum value with the mount -o remount.
You can use the quotasync command to synchronize the quota information from a node to the on-disk quota file between the automatic updates performed by GFS2.

Usage

Synchronizing Quota Information 
quotasync [-ug] -a|mntpnt...
u
Sync the user quota files.
g
Sync the group quota files
a
Sync all file systems that are currently quota-enabled and support sync. When -a is absent, a file system mountpoint should be specified.
mntpnt
Specifies the GFS2 file system to which the actions apply.
Tuning the Time Between Synchronizations 
mount -o quota_quantum=secs,remount BlockDevice MountPoint
MountPoint
Specifies the GFS2 file system to which the actions apply.
secs
Specifies the new time period between regular quota-file synchronizations by GFS2. Smaller values may increase contention and slow down performance.

Examples

This example synchronizes all the cached dirty quotas from the node it is run on to the ondisk quota file for the file system /mnt/mygfs2. 
# quotasync -ug /mnt/mygfs2
This example changes the default time period between regular quota-file updates to one hour (3600 seconds) for file system /mnt/mygfs2 when remounting that file system on logical volume /dev/volgroup/logical_volume. 
# mount -o quota_quantum=3600,remount /dev/volgroup/logical_volume /mnt/mygfs2