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Date: Mon, 22 Nov 2010 10:26:30 -0500
From: Jonathan Stewart <jonathan@kc8onw.net>
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To: Andrew Reilly <areilly@bigpond.net.au>
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Cc: stable@freebsd.org
Subject: Re: ZFS backups: retrieving a few files?
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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.

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.

HTH,
Jonathan