It happened early january, it happen now again - both disks of the server have failed. Today morning I got the message from the RAID about degraded array. Made few backups and reported that to my vendor.
Conclusion: Both disks needed to be replace, which happened afternoon. Server has been now rebuilt from the scratch, so I hope all things are working right now.
Please report back here if something is wrong.
The flood doors are open! Uploads via ADU are now activated. Please keep in mind that many people will try to upload their data, this leads to a busy server the next hours.