No disk space causes random errors

I'm sure most of you are aware of this but it's something that always takes me a long time to remember.

Whenever you have a seemingly random error on your Linux box - strange MySQL or Apache errors, being unable to write to a file that you could write to a moment ago, etc - always do a quick df -h to check how much disk space you've got left.

This problem is especially evident for those of us developing on virtual machines that often have limited disk space and so can run out easily. A quick recce of your /var/log/ (or equivalent) directory is a good starting point for freeing up space but you may also want to try find / -type f -size +50000k