RAID 4

RAID 4 and RAID 5 are similar, but RAID 4 holds all parity bits in a single drive. Data or files may be distributed among multiple, independently operating drives. This configuration facilitates parallel input/output (I/O) request performance. However, when parity bits are stored in a single drive for each block of data, system bottlenecks may result. When this occurs, system performance depends on parity drive performance.

RAID 4 advantages are as follows:

• Data block striping, which facilitates simultaneous I/O requests
• Low storage overhead, which lowers as more disks are added
• Does not require synchronized spindles or controller

RAID 4 disadvantages are as follows:

• Parity drives may lead to bottlenecks
• Slow random writes, which result when a parity must be separately written for each write