RAID and Subsystem Architectures RAID Configurations
RAID 6 – Block Striping
Unused space
Parity data File 3 File 2 File 1
Block B4 Block C1
Parity Parity
Block A1 Block A4
Reliability Read Performance
Write Performance
Block B1 Block B5 Block C2
Block A2 Parity Parity
Block B6 Parity
Block A7 Block B2
Block A3 Parity
Block C3
Block A8 Parity Parity
Block A5 Parity
Block A9 Block B3 Parity Parity
Block A6 Parity
RAID 6 (block striping with double distributed parity): Data is striped at the block level
Parity information is distributed across all disks Read performance is very good because data is spread across all drives Write performance is better than RAID 4 because there is no single parity drive to become a bottleneck, but performance is still inhibited by the parity calculation process RAID 6 is similar to RAID 5 but with two parity blocks instead of one and provides protection against a double disk failure.