I still get the "the discard operation is not supported" fstrim error when the LVs are set to "nopassdown" Seems that when I use ext4 the fstrim reports that it worked but the LVs Data% does not decrease after the fstrim. xfs just throws the error. I've also been looking at the output of lsblk -D # lsblk -D NAME DISC-ALN DISC-GRAN DISC-MAX DISC-ZERO xvdb 0 0B 0B 0 ├─data-pool00_tmeta 0 0B 0B 0 │ └─data-pool00-tpool 0 0B 0B 0 │ ├─data-pool00 0 0B 0B 0 │ └─data-data 0 0B 0B 0 └─data-pool00_tdata 0 0B 0B 0 └─data-pool00-tpool 0 0B 0B 0 ├─data-pool00 0 0B 0B 0 └─data-data 0 0B 0B 0 I expect the DISC-GRAN and DISC-MAX to be greater than 0B. On 20 January 2016 at 09:46, Chris Murphy <lists at colorremedies.com> wrote: > My guess? The passthrough is causing the error when the command passes > through to the actual device, which doesn't support Trim. > > I don't know how it actually works, but you can try to poke it with this > stick: copy a large file to this LV. Check the LV with lvdisplay. Delete > the file. Fstrim. Lvdisplay. Now compare the two lvdisplay results. > > It should show the PEs used are less after fstrim. > > > Chris Murphy > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos