Definition - What does RAID 4 mean?
RAID 4 is a Redundant Array of Independent Disks (RAID) standard configuration that uses block-level data striping and a dedicated disk for storing parity bits. It does not require synchronized spinning, and each disk functions independently when single data blocks are requested. This is in contrast to RAID 3, which stripes at block-level, versus bit-level. RAID 4 is similar to RAID 5, but RAID 4 does not distribute parity bits. This configuration requires at least three disks.
Techopedia explains 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