Brendan Hide posted on Sun, 04 May 2014 09:54:38 +0200 as excerpted: > From the man page section on -c: > "You must not specify clone sources unless you guarantee that these > snapshots are exactly in the same state on both sides, the sender and > the receiver. It is allowed to omit the '-p <parent>' option when '-c > <clone-src>' options are given, in which case 'btrfs send' will > determine a suitable parent among the clone sources itself." > > -p does require that the sources be read-only. I suspect -c does as > well. This means that it won't be so simple as you want your sources to > be read-write. Probably the only way then would be to make read-only > snapshots whenever you want to sync these over while also ensuring that > you keep at least one read-only snapshot intact - again, much like > incremental backups. I don't claim in any way to be a send/receive expert as I don't use it for my use-case at all. However... It's worth noting in the context of that manpage quote, that really the only practical way to guarantee that the snapshots are exactly the same on both sides is to have them read-only the entire time. Because the moment you make them writable on either side all bets are off as to whether something has been written, thereby killing the exact-same-state guarantee. =:^( *However*: snapshotting a read-only snapshot and making the new one writable is easy enough[1]. Just keep the originals read-only so they can be used as parents/clones, and make a second, writable snapshot of the first, to do your writable stuff in. --- [1] Snapshotting a snapshot: I'm getting a metaphorical flashing light saying I need to go check the wiki FAQ that deals with this again before I post, but unfortunately I can't check out why ATM as I just upgraded firefox and cairo and am currently getting a blank window where the firefox content should be, that will hopefully be gone and the content displayed after I reboot and get rid of the still loaded old libs, so unfortunately I can't check that flashing light ATM and am writing blind. Hopefully that flashing light warning isn't for something /too/ major that I'm overlooking! =:^( -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- 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
