RAID 3

Definition - What does RAID 3 mean?

RAID 3 is a Redundant Array of Independent Disks (RAID) standard that uses striping at the byte level and stores dedicated parity bits on a separate disk drive. Like RAID 2, RAID 3 requires a special controller that allows for the synchronized spinning of all disks. Instead of striping data blocks into different disks, RAID 3 stripes the bits, which are stored on different disk drives. This configuration is used less commonly than other RAID levels.

Techopedia explains RAID 3

Because RAID 3 combines parity and striping with stored parity bits on a dedicated disk, this configuration requires at least three separate hard disks - two for striping data and one for storing parity bits. The disks must spin in sync, so sequential read/write (R/W) operations achieve good performance. However, random R/W operations may take heavy hits in performance.

In actual terms, read speed is much greater than write speeds because of required checksum calculations, which is a performance bottleneck for the entire disk array.

RAID 3 advantages include:

  • High throughput for transferring large amounts of data
  • Resistant to disk failure and breakdown, which leads to RAID 3's main disadvantages (below).

Disadvantages:

  • The configuration may be too much if a small file transfer is the only requirement.
  • Disk failures may significantly decrease throughput.
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