Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Fri, Jan 10, 2014 at 05:55:47PM +0900, trex wrote: > On Wed, Jan 08, 2014 at 09:56:19PM +0900, trex wrote: > >> I built HA iSCSI targets with ocfs2+dual primary.(Ubuntu 13.04) > >> Each node has SSD raid with mdadm level0. > >> few days later, ocfs2 became frozen sometimes. > >> I figured out that it happens without TRIM. > >> But, I couldn't TRIM ssd raid because ocfs2 only supports offline TRIM(fstrim) and drbd 8.4.4 only supports online TRIM(discard). > >> Then, HOW CAN I TRIM SSDs on DRBD+OCFS2? > > > Uhm, to the linux block layer (including DRBD), there is no difference > > between what you call "online" or "offline" here. And whether you call > > it trim or discard or unmap, again, to the linux block layer, it is all > > the same thing. The differences are implementation details in the low > > level hardware drivers (scsi, fusion, etc.) > > > Did you actually try it? > > What happened? > > Error message? > > Logs? > > > Are you sure your SSD *and* MD properly support and propagate the > > discard capabilities and requests? > > First, ocfs2 doesn't have discard mount option. > It means you have to run FSTRIM for TRIM your ssd devices. > And it actually works.Some other filesystems are supporting automatic TRIM with discard option.(ex. btrfs, ext4 ) Still, the IO requests generated by whatever you use to do that are the same on the linux block level. > Second, you cannot TRIM on DRBD devices with FSTRIM. Yes I can. > There's a error message:"fitrim ioctl failed operation not supported" > Without DRBD, you can run FSTRIM on any filesystem. > So question is 'How trim filesystem on drbd which doesn't support discard mount option?' use fstrim ;-) Admittedly, this was not an ocfs2, I just did not have one handy. Still, it proves that fstrim works on top of DRBD. mount /dev/drbd0 /mnt/something fstrim -v /mnt/something /mnt/something: 1038696448 bytes were trimmed So if that does not work for you, something else is wrong. -- : Lars Ellenberg : LINBIT | Your Way to High Availability : DRBD/HA support and consulting http://www.linbit.com DRBD® and LINBIT® are registered trademarks of LINBIT, Austria. __ please don't Cc me, but send to list -- I'm subscribed