Owncloud supports several different types of “cache” mechanisms for increasing application performance and, in one particular case, expanding functionality (enabling File Locking).

The two types of caches I am going to discuss today are Redis and APCU. We will start with APCU.

If you have a stand-alone Owncloud installation and just need to optimize for better performance, then APCU is the way to go. It is very simple to get setup, with one small caveat on Ubuntu 14.04 (if you are running the latest LTS distro then this is where you live…).

The PHP5-APCU module is “out of date” relative to what owncloud will accept. So if you just install it with apt and then enable it in your owncloud config file you will get error messages in you logs at best or a more likely just a blank screen when you try to load your site.

So… here is a quick answer on how to fix this issue: (more…)