Michael, I am currently using rsync INSTEAD of btrfs backup tools. I
really don't see anyway that it could be compatible with the backup
features of btrfs. As I noted in my post, it is definitely not a
perfect solution, but it is doing the job for me. What I REALLY want in
this regard is n-way mirroring to get me out of the simplex trap
completely. At that point, I can have more confidence in btrfs snapshop
capability.
On 03/15/2014 04:35 AM, Michael Schuerig wrote:
On Thursday 13 March 2014 17:29:11 George Mitchell wrote:
I currently use rsync to a separate drive to maintain a
backup copy, but it is not integrated into the array like n-way would
be, and is definitely not a perfect solution.
Could you explain how you're using rsync? I was just about to copy a
btrfs filesystem to another disk. That filesystem has several subvolumes
and about 100 snapshots overall. Owing to COW, this amounts to about
1.2TB. However, I reckon that rsync doesn't know anything about COW and
accordingly would blow up my data immensely on the destination disk.
How do I copy a btrfs filesystem preserving its complete contents? How
do I update such a copy?
Yes, I want to keep the subvolume layout of the original and I want to
copy all snapshots. I don't think send/receive is the answer, but it's
likey I don't understand it well enough. I'm concerned, that a
send/receive-based approach is not robust against mishaps.
Consider: I want to incrementally back-up a filesystem to two external
disks. For this I'd have to for each subvolume keep a snapshot
corresponding to its state on the backup disk. If I make any mistake in
managing these snapshots, I can't update the external backup anymore.
Also, I don't understand whether send/receive would allow me to
copy/update a subvolume *including* its snapshots.
Things have become a little more complicated than I had hoped for, but
I've only been using btrfs for a couple of weeks.
Michael
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