Redundant Array of Independent Disks (RAID) systems provide storage by making the data on many small disks readily available to file servers, hosts, or the network as a single array. RAID systems use two or more drives in combination for fault tolerance and performance. One of the factors in data throughput and availability is how the data is stored within the array, that is, the array's RAID level.
On the system, disk drives within a tray are grouped together into RAID sets, also called virtual disks, according to their RAID level. The storage arrays support the following RAID levels:
RAID-5 results in excellent performance and good fault tolerance. Parity checking specifies that when the RAID controller writes information onto disks, it also writes redundant information called parity bits. If a disk fails, the parity information enables the RAID controller to re-create the lost information as it is requested. Since the parity information is spread across multiple disks, only a percentage of the disks is used for parity information, which improves the efficiency of available storage space.