Yet another mail-restore question...

[Henrique de Moraes Holschuh]

On Tue, 07 Jan 2003, Simon Matter wrote:
> I'm currently planning a new mailsystem so I'm interested in quick
> recovery in case something goes wrong.

Quick recovery means you need to shutdown the mail system, LVM-snapshot the
volume and restart it (if your system is well configured, this is quite
fast, and can be done at 04:00 in the morning ;-)).

Then, copy the LVM snapshot somewhere safe, and unfreeze it.

There are other ways, of course, but you asked for the quickest recovery
possible...

> My idea was the following:
> - Using XFS or ext3 filesystem (XFS is the preferred one)
> - Using LVM

You'll need both, unless XFS can snapshot by itself.  It is much faster than
ext3, btw. I'm using it for postfix spools, and will try it in Cyrus spools
one of these rainy days.

> - Having two servers. One real server and a 'snapshot' server.
> The snapshot server is built with cheap, big IDE drives. Using rsync,
> snapshots (well, sort of) are taken periodically and in the case of
> failure, data can be restored quickly from this box.

That won't work quite perfectly, but it could work well.  The mail messages
themselves are very rsyncable :-p  but if you want to make sure you won't
lose state, you will need to have plaintext backups of the mailboxes db, and
that the user is not using the mailbox when you copy it (due to the seen
db).

Still, it is what I would use myself, and there is a reason why the Cyrus
debian packages take a silent plaintext snapshot of the mailbox db to the
/var/backup directoriy every night by default :-P

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh