On 14 Sep 2017, Roman Mamedov said:
On Thu, 14 Sep 2017 16:02:31 +0100
Nix [off-list ref] wrote:
quoted
I would never consider snapshots on the same filesystem to be a backup
of anything, except possibly as a defence against 'oh whoops I rm'ed the
wrong tree'.
No one proposed that.
Oh I thought that was what people were proposing as the compelling btrfs
advantage.
The scenario is that the backup server would have its
rsync destination dir (from multiple other systems) periodically snapshotted,
providing a historic view of what it contained 1-2-3 months ago. Just like
"bup" does in userspace, I guess? -- or like rdiff-backup did, which I used
before. But now we have that directly in filesystem, no need to cling to
userspace crutches anymore.
I'm fairly sure that can't deduplicate anywhere near as effectively. No
dedup within files; no dedup across trees (very important if you have
duplicated data on multipl systems you are backing up); no dedup
anywhere except in immediate history. That's all rdiff-backup could do,
but the state of the art is better now.
--
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