ZFS backups: retrieving a few files?

[Andrew Reilly]

On Mon, Nov 22, 2010 at 10:26:30AM -0500, Jonathan Stewart wrote:
> On 11/22/2010 6:35 AM, Andrew Reilly wrote:
> >Dump/restore doesn't work for ZFS.  I *think* that I'm running
> >backups in the appropriate equivalent fashion: I take file
> >system snapshots (both absolute == level 0) and relative
> >(incremental), and zfs send those to files on the backup disk.
> 
> This is actively discouraged, there is no recovery ability when 
> receiving zfs streams so 1 bad bit would invalidate your entire backup.

Hmm.  Isn't that a problem that also affects the "sending
snapshots" scheme that you describe, below?

> The currently accepted practice is to create a ZFS file system on the 
> backup drive and just keep sending incremental snapshots to it.  As long 
> as the backup drive and host system have a snapshot in common you can do 
> incremental transfers.  This way you only have to keep the most recent 
> snapshot on the main system and can keep as many as you have space for 
> on the backup drive.  You also have direct access to any backed up 
> version of every file.

That sounds like a very cool notion.  Not unlike the
time-machine scheme.  Interesting how different capabilities
require going back and re-thinking the problem, rather than just
trying to implement the old solution with the new tools.

I'll see how I go with it...

Cheers,

-- 
Andrew