RAID 4: Independent Data disks with shared Parity disk

Characteristics/Advantages

1. Very high Read data transaction rate

2. Low ratio of ECC (Parity) disks to data disks means high efficiency

3. High aggregate Read transfer rate

Disadvantages

1. Quite complex controller design

2. Worst Write transaction rate and Write aggregate transfer rate

3. Difficult and inefficient data rebuild in the event of disk failure

4. Block Read transfer rate equal to that of a single disk

Each entire block is written onto a data disk. Parity for same rank blocks is generated on Writes, recorded on the parity disk and checked on Reads.

RAID Level 4 requires a minimum of 3 drives to implement