HowTo Disable The "relatime" Method For File "atime" Updates

Overview

atime

The "Access time" field for a file within a given file system is know as: "atime". When a process reads a file, the "atime" field is updated with the current date/time for this access. Disabling "atime" updates using the "noatime" mount flag is probably one of the biggest performance tweak that a Linux administrator can make. An active Linux server is continually reading files which generates a significant number of "atime" updates. This translates to numerous metadata updates made to the file system by writes to the physical disk which can lead to poor I/O performance.

relatime

Relative atime ('relatime') only updates the atime if the previous atime is older than the mtime or ctime. It avoids a lot of metadata atime updates (but not all of them, obviously, there's 'noatime' for that). It's like noatime, but useful for applications like mutt that need to know when a file has been read since it was last modified.