Red Hat GFS 5.2.1 -, Administrator'S Manual

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100 Chapter 9. Managing GFS
MountPoint
Specifies the directory where the GFS file system should be mounted.
9.9.1.2. Example
In this example, the GFS file system resides on the
pool0
block device and is mounted on directory
/gfs1/
with atime updates turned off.
mount -t gfs /dev/pool/pool0 /gfs1 -o noatime
9.9.2. Tune GFS
atime
Quantum
When
atime
updates are enabled, GFS (by default) only updates them once an hour. The time quan-
tum is a tunable parameter that can be adjusted using the
gfs_tool
command.
Each node in a GFS cluster updates the access time based on the difference between its system time
and the time recorded in the inode. It is required that system clocks of all nodes in a GFS cluster
be in sync. If a node’s system time is out of sync by a significant fraction of the tunable parameter,
atime_quantum
, then
atime
updates are written more frequently. Increasing the frequency of
atime
updates may cause performance degradation in clusters with heavy work loads.
By using the
gettune
action flag of the
gfs_tool
command, all current tunable parameters includ-
ing
atime_quantum
(default is 3600 seconds) are displayed.
The
gfs_tool settune
command is used to change the
atime_quantum
parameter value. It must
be set on each node and each time the file system is mounted. (The setting is not persistent across
unmounts.)
9.9.2.1. Usage
Displaying Tunable Parameters
gfs_tool gettune MountPoint
MountPoint
Specifies the directory where the GFS file system is mounted.
Changing the
atime_quantum
Parameter Value
gfs_tool settune MountPoint atime_quantum Seconds
MountPoint
Specifies the directory where the GFS file system is mounted.
Seconds
Specifies the update period in seconds.