3.8. Configuring atime Updates
3.8. 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 GFS2 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 or reduce the frequency of atime updates. Two methods of reducing the effects of atime updating are available: Mount with relatime (relative atime), which updates the atime if the atime update is older than the mtime or ctime update. Mount with noatime , which disables atime updates on that file system. 3.8.1. Mount with relatime The relatime (relative atime) Linux mount option can be specified when the file system is mounted. This specifies that the atime is updated if the atime update is older than the mtime or ctime update. Usage BlockDevice Specifies the block device where the GFS2 file system resides. MountPoint Specifies the directory where the GFS2 file system should be mounted. Example In this example, the GFS2 file system resides on /dev/vg01/lvol0 and is mounted on directory /mygfs2 . The atime updates take place only if the atime update is older than the mtime or ctime update. 3.8.2. Mount with noatime The noatime Linux mount option can be specified when the file system is mounted, which disables atime updates on that file system. Usage BlockDevice Specifies the block device where the GFS2 file system resides. MountPoint Specifies the directory where the GFS2 file system should be mounted. Example In this example, the GFS2 file system resides on /dev/vg01/lvol0 and is mounted on directory /mygfs2 with atime updates turned off.
mount BlockDevice MountPoint -o relatime mount /dev/vg01/lvol0 /mygfs2 -o relatime mount BlockDevice MountPoint -o noatime mount /dev/vg01/lvol0 /mygfs2 -o noatime