I am in the process of moving my sites from Slicehost to Linode, as most are aware Slicehost is being phased out for Rackspace Cloud. Anyway, I upgraded my VPS at Linode last night to Debian “Squeeze” and installed APC, which created a problem with the WordPress installations I had there. Basically, I couldn’t access the admin. Through the power of Twitter and the invaluable help of Mark Jaquith, I learned that by default APC doesn’t play nice with files that are checked out via Subversion. I think the root of my problem was a stray apc config for overriding include once, but certainly the subversion issue could have been at play too.
Anyway, a little Googling on the subject, I discovered there’s a configuration option for APC to use ctime instead of the default mtime. Adding
apc.stat_ctime=1 is all that is required.
Addendum To be clear, I install WordPress using Subversion and the appropriate tag. My Habari installs are also all Subversion checkouts from trunk.