Backing Up ZFS

Peter Schuller peter.schuller at
Sat Dec 20 09:20:13 UTC 2008

> I'm just curious at what others are currently doing to back up huge
> amounts of data. eg. 2TB and onwards.

I'm using rdiff-backup and some scripting to backup ZFS
snapshots. Other than the use of the ZFS snapshots there's nothing
special about it. If your use case is suitable for rdiff-backup, using
it with ZFS is a nice combination. For 2 TB+ I do suspect you would
want to divide that up into multiple distinct rdiff-backup sets and
indeed dependening on situation you may still have a problem with

In general I don't know that there is a lot ZFS specific to know about
backups other than the availability of snapshots, and other than the
potential to use zfs send/receive.

Personally I am reluctant to use ZFS send/receive at this stage,
because it is too dependent on ZFS. I would love to use it for
maintaining a hot standby machine, or having an almost-realtime backup
in the best case senario. But I would probably want a generic non-ZFS
specific backup as my primary backup as well. One risk that you want
to target with ZFS is that of a bug in ZFS itself; such bugs could
conceivably be such that it affects your zfs send/receive backup.

You mention:

> 3. ZFS -> Remote ZFS using RSync (Living in Australia, there are
> limits on data transfer of a few hundred GB per month, to costs are
> prohibitive)

rdiff-backup will be good in this senario too, giving you a rolling
window of history in addition to an up-to-date mirror. It does do
incremental updates including applying the rsync algorithm on
individual files. It is definitely slower, in terms of CPU usage, than
rsync however so if you have massive amounts of small files you may
feel there is an issue. That said, I'm using it regularly to backup
millions of files (e.g. collections of Maildir mailboxes).

I mention rdiff-backup but of course there are plenty of others. I
just happen to prefer rdiff-backup, mostly because of it's "rsync
mirror + history" semantics and completely trivial setup.

/ Peter Schuller

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