On Thu, Mar 19, 2015 at 8:34 PM, don fisher <hdf3@xxxxxxxxxxx> wrote: > Thanks. I will try that. How does the mount distinguish between /srv and > /usr11/srv if the subvol=srv is the same for both? It appears to work, for > when I do a df the sizes are different. I guess it can tell from the UUID of > / as opposed to that of /usr11. Yes, by fs volume UUID, it can differentiate between two subvolumes with the same name. But also by /dev/ if you use mount directly. A given volume can only have on srv subvolume. It could also have srv/srv and srv/srv/srv but it'll only have one of each of those. I missed that one completely. > > /dev/sdc2 20972544 6117628 14641012 30% /srv > /dev/sdb2 20972544 9492892 11112580 47% /usr11/srv > > I would still like to know why we need to mount the subvolumes at all. That's openSUSE's design for snapshots and rollbacks with snapper. For your backup purpose, you can just mount the top level and not mount the subvolumes individually, and your rsync will work fine. It will copy the right files to the right subvolumes by virtue of them being treated like directories. It's just that rsync can't create subvolumes (yet) so if you want an exact duplicate of an openSUSE install, you have to create the subvolumes in advance of rsync. > tried to dismount one of the subvolumes mounted on / and got a: > > umount: /var/log: target is busy Can't tell you what's going on. Reproduce this error and provide the current output from df and mount at the time. > > message, so could not test to /var/log access without a mount. It is easy to > access /usr11/var/log without it being mounted. Again, why mount it? Because the snapshots of root have an empty /var/log. To facilitate rollback, the static /etc/fstab always mounts these subvolumes in case the root is a rolled back snapshot. I > understood mounting partitions, because that was the only access. But the > appears to be two access channels here. Yes they are effectively bind mounts. You don't need to do this with your backup. -- Chris Murphy -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
