On Jan 16, 2014, at 3:44 PM, Kai Krakow <hurikha...@gmail.com> wrote:
> Chris Murphy <li...@colorremedies.com> schrieb: > >> >> On Jan 16, 2014, at 2:48 PM, Mirco Tischler <mircotisch...@gmx.net> wrote: >>> >>> Afair, you don't need to mount subvolumes. >>> >>> >> I do in this case in order to make sure there's an fstab in subsequent >> snapshots, that mounts the /var/log/journal subvolume. Otherwise, the >> booted snapshot will end up with a new /var/log/journal and all new >> journal entries which is not what I want. > > To fix this, you may want to boot into recovery, then snapshot your current > rootfs. Next, snapshot your var/log/journal into [subvol0]/var-log-journal, > which makes that a subvolume, rename var/log/journal into a backup location, > recreate var/log/journal as empty directory, add the fstab entry, then take > a new snapshot of your rootfs. > > This way you migrate to the new scheme while maintaining rolling back to the > old behavior. And it's easy to refix after rolling back to the old behavior > by just repeating the step "move journal", "create empty", "add fstab" and > it'll pickup your existing journal after booting back into normal mode. > > After a grace period you won't need your old rootfs snapshots any longer and > everything is good. > > It won't be that trivial if you'd made the var-log-journal within your > rootfs namespace (because after rolling back your subvolume is a subvolume > of a snapshot you'd rather delete, read: it's a sub-sub-volume). I tend to keep the original boot, root, home subvolumes as primary. So I think it's a bit weird having <FS_TREE>/root/var/log/journal as a subvolume that is then mounted on top of itself most of the time - as that's the way it would be in order for the fstab of subsequent root snapshots to mount the journal subvolume. Otherwise I'd have to change the fstab for each snapshot = annoying. So I think I'd put the journal subvolume in top level 5, or maybe in some other tree for persistent subvolumes to mount. Another limitation with fstab in a snapshot is that it has the wrong entries for the snapshot, those entries are only valid for the original subvolumes. So a snapshot of root subvolume called root.snap1, contains an /etc/fstab that calls for mounting subvol=root, rather than subvol=root.snap1. Making snapshots bootable poses some logistical challenges for legacy fstab, and also how to get them displayed in grub - some of the grub aspects have been discussed for several months on grub-devel@. Also, there's an argument to be made that a legitimate snapshot should initially be read-only. Upon rollback a rw snapshot would be created from the ro snapshot. Chris Murphy _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
