The file serve where all the homedir are stored is an NetApp Appliance, that include a lot of features. The 14 disks used by the device are configured in RAID level 5 mode. The Server has 3 spare disk that are used whe one or more of the “online” disks stop working. The change is done automatically by the system and a mail message is sent to the System Administrators and to the technical support that will send a new disk. The hardware substitution of the damaged disk(s) is done without interruption of the service.