The ext4 filesystem supports a 'relatime' option to avoid those extraneous small-I/O writes every time you touch a file. This isn't usually a big deal on single-spindle disks, but if you run a large server load on a RAID6 volume, for example, you add a lot of extra I/O for read-modify-write cycles.
One filesystem I've worked with actually had a setting for lazy atime updates, where you could specify granularity to say "If this file has been accessed in the last X hours, don't bother updating it again." This allows you to cut down on extra small I/Os and not break things like HSM batch jobs.
Look in /proc/mounts to see if your root filesystem has the relatime bit set. You can specify atime, relatime, and noatime in /etc/fstab to explicitly set the behavior.
If you really need atime, turn it on. You can do so without unmounting like this:
# mount -o remount,atime /
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Quote:
Originally Posted by
Corona688
ext4 also has some "extended" attributes you can set on files, try lsattr filename to see if anything weird got put on them.
Good point - the "A" attribute can be set on a file or directory to prevent atime updates selectively.