RAID 5 is a compromise between the performance of RAID 0 and the data protection of
RAID 1. Performance is improved by striping data across the drives in the set. Data
protection is provided by parity information that is distributed across the drives. Data
can be recovered if any single drive fails. RAID 5 leaves you with more usable space
than RAID 1. RAID 5 needs only the equivalent of one drive’s worth of disk space to
store the parity information. You can create a RAID 5 set using either three or four disks.