RAID 4 A RAID 4 requires a minimum of 3 hard drives to configure. Each entire block of a RAID 4 is written onto a data disk. Parity for the same rank blocks are generated on writes, recorded on the parity disk, and then checked on reads. In some installations a RAID 4 array can recover from multiple and simultaneous hard drive failures. A RAID 4 has the worst write rate of all RAID designs, and has a very complex controller setup which makes it very complicated to setup. However, a RAID 4 reads rapidly and is highly efficient.
