Re: Using tarsnap for disaster recovery

[Colin Percival <cperciva@tarsnap.com>]

On 06/02/11 09:19, Hywel Mallett wrote:
> I've been using tarsnap for a while for backing up a single server
> (actually a few, but only one is relevant to this question).
> The scenario is that this FreeBSD server backs up /usr/local and a few
> bits of /var with each backup. The backup works fine, and a disaster
> recovery has been tested onto alternate hardware (install a base FreeBSD
> system with tarsnap, install the tarsnap.key and restore from the latest
> backup), and it works nicely.

Wow, someone who actually tests backups?  Amazing, I didn't know such
people existed. ;-)

> The question is what do I have to consider as far as tarsnap is
> concerned? Once we've restored to alternate hardware we'll want to
> continue to backup using tarsnap. /usr/local/tarsnap-cache is empty
> after the restore (as it's ignored during backup by tarsnap). Will we
> need to run tarnap --fsck before re-enabling the backups to rebuild the
> cache? Will the fscked data be valid, if data is laid out differently on
> disk?

Yes and yes.  The state regenerated by --fsck tells tarsnap what is on
the server side; your local filesystems don't matter to it at all.

-- 
Colin Percival
Security Officer, FreeBSD | freebsd.org | The power to serve
Founder / author, Tarsnap | tarsnap.com | Online backups for the truly paranoid