It’s never much fun upgrading major versions of operating systems and I always get slightly uncomfortable during the process. Knowing you have a good backup is always handy (thanks linode). In this case I was going from Debian 5 to 6 and as usual, the Debian folks have made it smooth sailing.
This guide on the linode pages was very useful:
All went smoothly when I upgraded my linode from Lenny to Squeeze except that mysql would not start.
This post http://www.robtucker.co.uk/2009/05/16/upgrading-mysql-50-to-51-on-debian-50 had the answer I needed.
In short, I had to comment out the ‘skip-bdb’ entry in /etc/mysql/my.cnf and then issue:
apt-get -f install mysql-server