On Mon, Nov 24, 2014 at 12:23 AM, Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > On Sun, Nov 23, 2014 at 3:06 PM, John Tall <mjtallx@xxxxxxxxx> wrote: > >>> See if this works while you're at it: >>> # mount -o remount,discard / >>> >>> And then check mounts. It should now show discard is enabled. >> >> Unfortunately not, it does not show discard in /proc/mounts. > > Ed Greshko points to the cause for this, looks like discard can't be > added with remount. So now I think I know what's going on: > > Systemd mounts the root device read only at /sysroot, and only then > can it read fstab to know what the mount options are. It then remounts > rw and includes the mount options in fstab. So any options that aren't > supported by remount, won't work. > > What's odd is that I'm certain discard worked for root on Btrfs, so I > wonder if this remount limitation is XFS only or if it applies to any > filesystem? In which case, how is anyone getting trim to work on the > root device? > > The only answer I'm thinking of is pretty obscure: use boot parameter > rootflags=discard. The rootflags= parameter accepts mount options and > applies them to the volume defined by root=. I only know this because > Btrfs installs depend on rootflags=subvol=<rootname> to mount the > correct subvolume containing root, and subvol=<name> is just a repeat > of what's in fstab (typically). It worked after adding rootflags=discard to /etc/default/grub and running grub2-mkconfig. Thanks for the help! J -- test mailing list test@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe: https://admin.fedoraproject.org/mailman/listinfo/test
