UNIX for Dummies Questions & Answers

Well, I'm surprised.

Could you post the contents of /etc/fstab?

Code:

# /etc/fstab: static file system information.
#
# Use 'blkid -o value -s UUID' to print the universally unique identifier
# for a device; this may be used with UUID= as a more robust way to name
# devices that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    nodev,noexec,nosuid 0       0
/dev/sda1       /               ext4    errors=remount-ro 0       1
# swap was on /dev/sda5 during installation
UUID=db350323-a657-441e-b8d2-9b472700026a none            swap    sw              0       0

Thanks for any help.

Could you ls -ld the directories the files reside in? I noticed one of them was named "tmp" and am wondering if it had any weird permissions like the sticky bit set on it.

I wouldn't expect that to prevent atimes from working, but that's the only obvious difference I see between the two locations.

ext4 also has some "extended" attributes you can set on files, try lsattr filename to see if anything weird got put on them.

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 /

---------- Post updated at 02:10 PM ---------- Previous update was at 02:04 PM ----------

Good point - the "A" attribute can be set on a file or directory to prevent atime updates selectively.