Marc MERLIN posted on Sun, 20 Apr 2014 12:46:27 -0700 as excerpted: > Long story short, I'm wondering if I can use btrfs send to copy sub > subvolumes (by snapshotting a parent subvolume, and hopefully getting > all the children underneath). My reading so far, says no.
I don't do much with subvolumes and absolutely nothing with send/receive myself, but from what I've read, no, for the simple case (but see below) that cannot work. The reason is that snapshots (including the read-only snapshot done for a send) stop at subvolume borders. In the large-internal-write-NOCOW-file dedicated subvolume case, that's a positive, since the dedicated subvolume can be used to avoid snapshotting the nocow stuff on the subvolume when snapshotting a parent, but in this case the same subvolume property is a negative. Now somebody *DID* mention multi-subvolume sends, and indeed, checking the manpage, there appears to be allowance for that by naming multiple subvolumes (and multiple clone-sources when doing the incremental), *BUT*, there appears to be no corresponding allowance for multiple subvolume snapshotting, so your script would need a "for subvol in $subvols" type construct at least for the snapshotting, and once you do that, you might as well do multiple sends as well, as that's likely to be more robust than a the larger all-in-one send, if one of the subvolume sends/receives fails for some reason. -- 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 [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
