Upgraded to Debian Wheezy last night. Followed the official upgrade instructions. Things went generally well and I’m amazed by how well major upgrades go with Debian. Wheezy is the second major release for this particular server and it had an uptime of 476 days before today’s upgrade.
A couple problems were noted, specifically with the upgrade of the mysql server and dovecot. Both seem to have breaking changes. For MySQL, the breaking change is that in MySQL server 5.5 the master-host and other master-* options are no longer supported. See the MySQL manual for more details. I commented out the various replication-related options in /etc/mysql/my.cnf for now and will need to fix that quickly.
The other break-change on this computer was with dovecot. Looks like all of the dovecot options are now split into multiple files in /etc/dovecot/conf.d with the traditional dovecot.conf now being a shell that refers to other files. For this particular server I needed to change the path to the SSL certificates; now dovecot wants them in the /etc/dovecot hierarchy and I needed to change the mail_location to be Maildir rather than mbox (not sure why that was the new default now) and add mail_privileged_group of mail. Dovecot’s working now.
Among the fun things that I’ve already discovered is that I can mount a Synology SMB share without “file exists” problems and airprint finally works for me (though we’ll see for how long).
Once I get comfortable with the stability of the new system I’ll begin migrating other, more mission-critical, servers.