One of our 4 hard drives started to fail on the 2nd of February. Once some checks were ran, it failed completely and was replaced. The RAID array was rebuilt but we still have a hardware issue. I've taken a copy of the database and tested it on another server, it's fine. Datacenter techs are trying to find the cause of the hardware error (I suspect another HDD or the RAID controller).
Update: The RAID controller is being replaced, or would be if there were any spare, there isn't. We'll see how long it will take them to get another, we'll probably end up moving to their US based datacenter.