3.10. Configuring `atime` Updates

Each file inode and directory inode has three time stamps associated with it:

ctime — The last time the inode status was changed
mtime — The last time the file (or directory) data was modified
atime — The last time the file (or directory) data was accessed

If atime updates are enabled as they are by default on GFS and other Linux file systems then every time a file is read, its inode needs to be updated.

Because few applications use the information provided by atime, those updates can require a significant amount of unnecessary write traffic and file-locking traffic. That traffic can degrade performance; therefore, it may be preferable to turn off atime updates.

Two methods of reducing the effects of atime updating are available:

Mount with noatime
Tune GFS atime quantum

3.10.1. Mount with `noatime`

A standard Linux mount option, noatime, can be specified when the file system is mounted, which disables atime updates on that file system.

Usage

mount BlockDevice MountPoint -o noatime

BlockDevice: Specifies the block device where the GFS file system resides.
MountPoint: Specifies the directory where the GFS file system should be mounted.

Example

In this example, the GFS file system resides on the /dev/vg01/lvol0 and is mounted on directory /gfs with atime updates turned off.

mount /dev/vg01/lvol0 /gfs -o noatime