Musings on ZFS Backup strategies

Daniel Eischen deischen at
Fri Mar 1 20:34:40 UTC 2013

On Fri, 1 Mar 2013, Ben Morrow wrote:

> Quoth Daniel Eischen <deischen at>:
>> Yes, we still use a couple of DLT autoloaders and have nightly
>> incrementals and weekly fulls.  This is the problem I have with
>> converting to ZFS.  Our typical recovery is when a user says
>> they need a directory or set of files from a week or two ago.
>> Using dump from tape, I can easily extract *just* the necessary
>> files.  I don't need a second system to restore to, so that
>> I can then extract the file.
> As Karl said originally, you can do that with snapshots without having
> to go to your backups at all. With the right arrangements (symlinks to
> the .zfs/snapshot/* directories, or just setting the snapdir property to
> 'visible') you can make it so users can do this sort of restore
> themselves without having to go through you.

It wasn't clear that snapshots were traversable as a normal
directory structure.  I was thinking it was just a blob
that you had to roll back to in order to get anything out
of it.

Under our current scheme, we would remove snapshots
after the next (weekly) full zfs send (nee dump), so
it wouldn't help unless we kept snapshots around a
lot longer.

Am I correct in assuming that one could:

   # zfs send -R snapshot | dd obs=10240 of=/dev/rst0

to archive it to tape instead of another [system:]drive?


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