RAID 3

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.

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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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Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…