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RAID configurations

by Kyluke McDougall on 19 January 2015

What does it all mean, when do I use what?

What Is RAID?

RAID stands for redundant array of inexpensive disks; or now more commonly redundant array of independent disks.

The idea of RAID is to use multiple disk in conjunction with each other to create 1 logical Volume. For example, you would use RAID to couple together 4x1TB hard drives to create what looks like 1 4TB hard drive. Each RAID configuration has it's own purpose and will be used for completely different applications.

For instance, RAID 1 would be used for backup purposes and redundancy while RAID 5 would be used to create larger logical volumes out of many smaller hard drives.

Have a look at the table below. It breaks down each configuration by it's name and description.

Level Description Minimum Drives Fault tolerance Read perf. Write perf.
RAID 0 Block-level striping without parity or mirroring 2 0 (none)
RAID 1 Mirroring without parity or striping 2 n−1 drives
RAID 2 Bit-level striping with dedicated Hamming-code parity 3 One drive (Varies) (Varies)
RAID 3 Byte-level striping with dedicated parity 3 One drive (n−1) (n−1)
RAID 4 Block-level striping with dedicated parity 3 One drive (n−1) (n−1)
RAID 5 Block-level striping with distributed parity 3 One drive n (n−1)
RAID 6 Block-level striping with double distributed parity 4 Two drives n (n−2)
RAID 1+0 Mirroring without parity, and block-level striping 4 One or more drives per span (n/spans)