Linux says my space is full with 2.4/50gb used

You're using an OpenVZ-based VPS, and on this VPS your root filesystem isn't really a filesystem, but a directory on the host. That directory on the host has run out of disk space.

This is a strong sign that your provider has significantly overcommitted resources and isn't monitoring them well, or at all. The replacement for simfs, known as ploop, is more difficult to overcommit, has a stronger guarantee of disk space, and performs better.

I would strongly advise you to find another provider as soon as possible. This is very unlikely to be the last problem you will have with your current one. (And, of course, one not based on OpenVZ.)