This level takes a block of data and breaks it up into stripes that are recorded across two or more drives. Parity information for each data stripe is recorded on a single additional drive. RAID 3 is infrequently used in hard drive RAID systems, but it is used in tape arrays. This is similar to RAID 3 except that instead of creating parity for each stripe of data, parity is created for the entire data block. RAID 4 supports higher transaction rates.
Parity is checked on each block rather than each stripe.
However, instead of a single dedicated parity disk, the parity information is striped on the data disks along with the blocks themselves. Transaction rates are high, but write speed is penalized as the RAID 5 controller has to avoid placing data blocks and associated parity information on the same disks. A combination of RAID 5 and RAID 3. RAID Glossary Block. A string of data elements recorded, processed or transmitted as a unit.