On 03/04/13 01:08, Eric Sandeen wrote:
On 4/1/13 5:26 PM, Steven Haigh wrote:
On 04/02/2013 12:19 AM, Josef Bacik wrote:
On Sat, Mar 30, 2013 at 9:38 PM, Steven Haigh netwiz@crc.id.au wrote:
Hi all,
Firstly, Please CC me into replies as I'm not subscribed to this list.
I'm trying to confirm that Fedora 18 has enabled trim for XFS filesystems. I have added discard to the mount options in /etc/fstab - however I do not see it when looking at the output of 'mount':
...
Can anyone share some insight into this?
IIRC you have to rebuild your initrd so it picks up the new fstab mount options for /, the other options is you should be able to do mount -o remount,discard /. Thanks,
Hi Josef,
This was the basis of my query - even after a remount with the discard option, 'discard' still wasn't present in the options - as seen by the mount line quoted above.
Sorry I didn't see this earlier. Josef is right; discard is not a remountable option on xfs, unfortunately (only inode64 and barrier options are remountable today). So you could either put the option in the rootflags= kernel commandline parameter, or rebuild the initrd after adding it to fstab as Josef suggested so that it's initially mounted with the option.
Thanks for the reply Eric. I believe it would be helpful if this was documented. I was expecting it to work the same way as ext4 - being a simple remount would enable the discard option. Once that didn't work - and especially as I didn't get an error in either the syslog or returned from the command, I was starting to think it was a bug in the implementation of TRIM in XFS.
I wonder if we should add something to the remount path to printk when a non-remountable option is encountered; I might look into that, otherwise it's a little surprising (although semi-obvious when the problem doesn't show up in /prcoc/mounts...).
I think this is probably the best way to handle things. The first thing I did was to look at the return code from mount (which returned 0 - ie success), then dmesg, then /var/log/messages. As I found nothing, I had no hints on where to look.
The wiki page[1] for XFS does state that XFS supports TRIM - and it mentions the changes to /etc/fstab to enable it. It doesn't however mention that it needs to be on the initial mount - or that a remount will not enable it.
The best of both worlds would be to have it output to the dmesg - or even fail the mount command (if that is an option?) just like ext4 would if you supply a bogus option set.
1: http://xfs.org/index.php/FITRIM/discard