Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I've got an OCZ RevoDrive 3 mounted as / on my CentOS 6.3 box running kernel 2.6.32-220.17.1.el6.x86_64. /boot is on a HDD since OCZ's driver apparently doesn't yet support booting directly to it. While testing, the drive mounted with the 'discard' option just fine. It only seems to be disabling itself after mounting automatically via fstab.

The option shows up in mount:

[root@craft ocz]# mount
/dev/sdb3 on / type ext4 (rw,noatime,discard)

But /var/log/messages says:

Aug 12 04:49:53 craft kernel: EXT4-fs warning (device sdb3): release_blocks_on_commit: discard not supported, disabling

I attempted to test if it was working anyways with hdparm, but an issue that I assume is unrelated to this one causes hdparm to segfault when trying to --read-sectors, so I'm not sure what else to check.

Anyone know how I could get discard working properly?

Update: /etc/fstab line for the partition in question, as requested in comments:

UUID=a869cf38-7547-49a9-aeb5-17adb56b4bd4 / ext4 defaults,noatime,discard 1 2

share|improve this question
Could you post your fstab line for /dev/sdb3? – grs Aug 12 '12 at 19:03
@grs Done. I should've thought to do that in the first place! – Seventoes Aug 13 '12 at 0:12
Does hdparm -I /dev/sdb | grep -i trim have any output? – Charles Aug 13 '12 at 1:05
@Charles, Yup! Supported: * Data Set Management TRIM supported and * Deterministic read after TRIM – Seventoes Aug 13 '12 at 6:41

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.