RAID and Subsystem Architectures RAID Configurations
RAID 3 – Byte Striping
Unused space
Parity data File 3 File 2 File 1
Reliability Read Performance
Write Performance
Parity Block B4 Block C1
Bytes 1,4,7… Bytes 2,5,8…
Block B2 Block B6
Bytes 3,6,9…
Parity Parity Parity Parity Parity
Block B1 Parity
RAID 3 (byte striping with dedicated parity disk): Data is striped at the byte level Parity information is XOR function generated at write speed and written to dedicated parity disk
Read performance is very good because data is spread across all drives Write performance is better than RAID 5, Writes to same place on each drive. Disks must be synchronised Minimum write is complete stripe so no interleaved writes Seek requires all disks to seek so small access impacts performance Ideally suited to long contiguous reads and writes from a single system, e.g. streaming data