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@xxxxxxxxxx https://lists.centos.org/mailman/listinfo/centos