Red Hat GFS 6.0 -, Administrator'S Manual

Page: 111 / 192

Chapter 9. Managing GFS 97
9.4.3. 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 synchro-
nizations is a tunable parameter,
quota_quantum
, and can be changed using the
gfs_tool
com-
mand. 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.)
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.
9.4.3.1. 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 val-
ues may increase contention and slow down performance.
9.4.3.2. 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