Acer Altos R920 Series - Manual (Page 197)

179
Overview
The system may be equipped with a SAS or SAS RAID configuration
utility (depending on your system configuration). You can use these
utilities for configuring the internal hard disks.
Caution: Creating a RAID volume erases all data previously saved
in the hard drives. Make sure that you back up important files
before starting a RAID configuration process.