The file server that record all the homedir (the personal directories of all users) is a NetApp Appliance, that include a lot of features to prevent the loss or damage of datum.
The 14 disks used by the device are configured in RAID level 5 mode, this means that even in case of failure of one or more disks, the datum recorded are safe. 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.

The second option that help a user to maintain his/hers files is the .snapshot feature. Refer to this page in order to understand and use it.