On Thu, Jan 6, 2011 at 1:42 PM, Carl Cook <cac...@quantum-sci.com> wrote: > On Thu 06 January 2011 11:16:49 Freddie Cash wrote: >> > Also with this system, I'm concerned that if there is corruption on the >> > HTPC, it could be propagated to the backup server. Is there some way to >> > address this? Longer intervals to sync, so I have a chance to discover? >> >> Using snapshots on the backup server allows you to go back in time to >> recover files that may have been accidentally deleted, or to recover >> files that have been corrupted. > > How? I can see that rsync will not transfer the files that have not changed, > but I assume it transfers the changed ones. How can you go back in time? Is > there like a snapshot file that records the state of all files there?
I don't know the specifics of how it works in btrfs, but it should be similar to how ZFS does it. The gist of it is: Each snapshot gives you a point-in-time view of the entire filesystem. Each snapshot can be mounted (ZFS is read-only; btrfs is read-only or read-write). So, you mount the snapshot for 2010-12-15 onto /mnt, then cd to the directory you want (/mnt/htpc/home/fcash/videos/) and copy the file out that you want to restore (cp coolvid.avi ~/). With ZFS, things are nice and simple: - each filesystem has a .zfs/snapshot directory - in there are sub-directories, each named after the snapshot name - cd into the snapshot name, the OS auto-mounts the snapshot, and off you go Btrfs should be similar? Don't know the specifics. How it works internally, is some of the magic and the beauty of Copy-on-Write filesystems. :) -- Freddie Cash fjwc...@gmail.com -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
