xn11 is currently suffering from some I/O issues again, this is currently being worked on. Further updates will follow
Update: The system has been rebooted, the RAID is in a degraded state but there are no signs of any disk issues. The RAID is now rebuilding, and the degraded disk has been noted as it may require replacement. As unlikely as it is, drives are around the same age so it could be a second faulty disk in a month. We will continue to keep a close eye on this server.