ZFS backups: retrieving a few files?

[Andrew Reilly]

On Tue, Nov 23, 2010 at 01:56:01PM +0100, Thomas Ronner wrote:
> On 11/23/10 1:45 PM, Andrew Reilly wrote:
> >No, I don't like tar, rsync and friends for backups: they don't
> >deal well with hard links, special files or sparse files.
> 
> rsync -avHxS --delete --numeric-ids /src/. /dst/.
> 
> Handles sparse files (S) and hard links (H). Never had any trouble with 
> special files. What sort of special files are not handled correctly by 
> rsync? I'd like to know because I'm relying on rsync for backups for 
> years on my home network.

I remember having problems with hard links, but it's possible
that I wasn't using rsync correctly.  Of special files, I don't
remember non-dump backups doing well with the unix-domain
sockets that were liberally used and tricky to set up right for
djb's daemon-tools.  Most uses of sockets put them in /tmp,
don't get backed up, and they don't need to persist.  Dan puts
them in /var, and they're expected to persist across reboots,
which means they need to be backed-up.  Maybe rsync and modern
tar handle these OK, but I remember at least one of them getting
wedged just trying to read one as a file.

The special files in /dev used to be a problem too, but that's
gone away, now that we have devfs.

I really like dump/restore.  I expect that I will miss them.

Cheers,

-- 
Andrew