The NAS is currently down because of a major crash. First one HD broke down which I replaced a few hours ago, but then during the rebuild of the raid array, another HD crashed which made the volume corrupt. I'm working on a backup right now and also contacted Synology for this problem. Bare in mind that there could be a lot of free space when I get this thing going again..
I got new drives for the NAS and was trying to rescue stuff. This takes several weeks to recover so I decided to delete all shit and rebuild from scratch..