Red Hat Summit4.9. Configuring atime Updates
Each file inode and directory inode has three time stamps associated with it:
ctime— The last time the inode status was changedmtime— The last time the file (or directory) data was modifiedatime— 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
atimequantum
4.9.1. Mount with noatime
Copy linkLink copied to clipboard!
A standard Linux mount option,
noatime, can be specified when the file system is mounted, which disables atime updates on that file system.
Usage
Copy linkLink copied to clipboard!
mount -t gfs BlockDevice MountPoint -o noatime
mount -t gfs 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
Copy linkLink copied to clipboard!
In this example, the GFS file system resides on the
/dev/vg01/lvol0 and is mounted on directory /gfs1 with atime updates turned off.
mount -t gfs /dev/vg01/lvol0 /gfs1 -o noatime
mount -t gfs /dev/vg01/lvol0 /gfs1 -o noatime
'%20d='M201.5%20305.5c-13.8%200-24.9-11.1-24.9-24.6%200-13.8%2011.1-24.9%2024.9-24.9%2013.6%200%2024.6%2011.1%2024.6%2024.9%200%2013.6-11.1%2024.6-24.6%2024.6zM504%20256c0%20137-111%20248-248%20248S8%20393%208%20256%20119%208%20256%208s248%20111%20248%20248zm-132.3-41.2c-9.4%200-17.7%203.9-23.8%2010-22.4-15.5-52.6-25.5-86.1-26.6l17.4-78.3%2055.4%2012.5c0%2013.6%2011.1%2024.6%2024.6%2024.6%2013.8%200%2024.9-11.3%2024.9-24.9s-11.1-24.9-24.9-24.9c-9.7%200-18%205.8-22.1%2013.8l-61.2-13.6c-3-.8-6.1%201.4-6.9%204.4l-19.1%2086.4c-33.2%201.4-63.1%2011.3-85.5%2026.8-6.1-6.4-14.7-10.2-24.1-10.2-34.9%200-46.3%2046.9-14.4%2062.8-1.1%205-1.7%2010.2-1.7%2015.5%200%2052.6%2059.2%2095.2%20132%2095.2%2073.1%200%20132.3-42.6%20132.3-95.2%200-5.3-.6-10.8-1.9-15.8%2031.3-16%2019.8-62.5-14.9-62.5zM302.8%20331c-18.2%2018.2-76.1%2017.9-93.6%200-2.2-2.2-6.1-2.2-8.3%200-2.5%202.5-2.5%206.4%200%208.6%2022.8%2022.8%2087.3%2022.8%20110.2%200%202.5-2.2%202.5-6.1%200-8.6-2.2-2.2-6.1-2.2-8.3%200zm7.7-75c-13.6%200-24.6%2011.1-24.6%2024.9%200%2013.6%2011.1%2024.6%2024.6%2024.6%2013.8%200%2024.9-11.1%2024.9-24.6%200-13.8-11-24.9-24.9-24.9z'/%3e%3c/svg%3e){kind=small}