When I took my current job, I inherited administration of a postfix-based mail server running debian etch. We're running nightly backups, but the server is on old hardware and a single hard drive, so no redundancy there. I'm getting ready to repurpose a beefier server with RAID 5, and plan to match the current software setup (Postfix, Dovecot, with MySQL for the user database). However, with close to 50 GB of mail already on the server, it's going to take a minute or ten to copy it over the network. Even with doing the maintenance at night, management wants minimal loss of messages. I'm anticipating it taking more than just a minute or two to get everything working on the new server, so what I would like to do is let Postfix queue up messages while the migration is in progress, then have them delivered to the new server once it is active.

I've done some googling, but haven't found anything useful. I'm going to continue looking, but I was wondering if anyone knew of a good resource of information on performing this kind of migration.

Perhaps I'm missing the point, but why not set up the new server ready & waiting then change the MX record to point to the new server. Then when all mail is hitting the new one, move the data from the old server to the new one?

Carl.

I had considered doing that, but stopped considering it for some reason. I honestly don't remember why. Now I feel a bit silly, haha.

Don't worry, I've asked some real howlers on here myself. Perhaps you'll remember the reason when it all fails ;-)

Carl.

Above and beyond that, you don't lose mail if your server isn't available at time of delivery. It should queue it up on the originating server for several hours at least before giving up on delivery. Biggest thing to watch is the ttl on your dns records... it's bad if transition takes 3 days because that's the absurd value someone gave it.

Shutdown mail on both servers, change mx record, copy messages, bring up mail on new server (preferably accepting mail at both the original and new ip.)