I accidentally started my first run of subsonic as root, everything was fine. I stopped it and restarted as the user I created, after chown-ing the files.
It said that it ran fine but I was unable to connect to the service. Poking through the logs, it seems that there are files in /tmp which are left over and I need to change the ownership on those, but it stopped the service working properly.
14193 [main] ERROR org.springframework.web.context.ContextLoader - Context initialization failed
[snip]
Could not create disk store. Initial cause was Index file /tmp/subsonic/ehcache/musicFolderCache.index could not created.
