RAID (Redundant Arrays of Independent Disks) is the name of an architecture for providing fault-tolerant and high-performance volumes and LUNs. Here a number of individual disk drives are combined to form a transparent network, the RAID group. So-called Logical Unit Numbers (LUNs) are defined for these RAID groups. It is typical that multiple LUNs (logical volumes) are configured on the same RAID group. For information on the effects of logical volumes on the performance, see “Logical volumes and physical disks”.
All ETERNUS DX and Symmetrix storage systems are high-availability systems which not only comply with the RAID standards originally defined by Berkeley University, but also meet all the availability levels specified by the RAID Advisory Board. They differ only in their configuration options. The following RAID levels are usual in the BS2000 environment:
RAID 1 (full mirror)
RAID 1/0 (striping + full mirror)
RAID 5 (striping + parity mirror)
RAID 6 (striping + dual parity mirror)