On Sun, Mar 26, 2017 at 02:14:36PM +0500, Roman Mamedov wrote: > You could have done time-based snapshots on the top level (for /backup/), say, > every 6 hours, and keep those for e.g. a month. Then don't bother with any > other kind of subvolumes/snapshots on the backup machine, and do backups from > remote machines into their respective subdirectories using simple 'rsync'. > > That's what a sensible scheme looks like IMO, as opposed to a Btrfs-induced > exercise in futility that you have (there are subvolumes? must use them for > everything, even the frigging /boot/; there is send/receive? absolutely must > use it for backing up; etc.)
Using old boring rsync is actually a pretty good idea, with caveats. I for one don't herd server farms, thus systems I manage tend to be special snowflakes. Some run modern btrfs, some are on ancient kernels, usually / is on a mdraid with a traditional filesystem, I got a bunch of ARM SoCs at home -- plus even an ARM hosted server at Scaleway. Standardizing on rsync lets me make all those snowflakes backup the same way. Only on the destination I make full use of btrfs features. Another benefit of rsync is that I don't exactly trust that send from 3.13 to receive on 4.9 won't have a data loss bug, while rsync is extremely well tested. On the other hand, rsync is _slow_. Mere stat() calls on a non-trivial piece of spinning rust can take half on hour. That's something that's fine in a nightly, but what if you want to back important stuff every 3 hours? Especially if those are, say, Maildir mails -- many many files to stat, almost all of them cold. Here send/receive shines. And did I say that's important stuff? So you send/receive to one target every 3 hours, and rsync nightly to another. -- ⢀⣴⠾⠻⢶⣦⠀ Meow! ⣾⠁⢠⠒⠀⣿⡁ ⢿⡄⠘⠷⠚⠋⠀ Collisions shmolisions, let's see them find a collision or second ⠈⠳⣄⠀⠀⠀⠀ preimage for double rot13! -- 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
