My backup use case is different from the what has been recently discussed in another thread. I'm trying to guard against hardware failure and other causes of destruction. I have a btrfs raid1 filesystem spread over two disks. I want to backup this filesystem regularly and efficiently to an external disk (same model as the ones in the raid) in such a way that * when one disk in the raid fails, I can substitute the backup and rebalancing from the surviving disk to the substitute only applies the missing changes. * when the entire raid fails, I can re-build a new one from the backup. The filesystem is mounted at its root and has several nested subvolumes and snapshots (in a .snapshots subdir on each subvol). Is it possible to do what I'm looking for? Michael -- Michael Schuerig mailto:michael@schuerig.de http://www.schuerig.de/michael/ -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html