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RAID Level

RAID Level

RAID level is a number indicating the type of organisation of disks in the RAID array:

RAID 0	Striping. No redundancy.	Fastest. Provides maximum storage. No fault tolerance.
RAID 1	Disk mirroring.	Good performance. Fault tolerant. Only fault tolerant option if using 2 drives.
RAID 2	Error correction data written to separate disk.
RAID 3	Striping (small stripe size) with one parity disk.
RAID 4	Striping (large stripe size) with one parity disk.
RAID 5	Striping with parity. Parity information is distributed across all drives.	Good performance. Fault tolerant. Slowest to rebuild (if one disk is replaced). Better storage than RAID 1. Requires at least 3 disks. Tolerant of a single disk failure.
RAID 6	RAID 5 with an extra parity disk.	Tolerant of two disks failing.
RAID 0+1	Mirrored array (RAID 1) whose segments are RAID 0 arrays, i.e. mirroring of striped sets.
RAID 10	Striped array (RAID 0) of mirrored sets (RAID 1).
RAID 53	Combination of RAID 0 and RAID 3. Each stripped set (of RAID 0) are RAID 3 sets.

RAID 1 (disk mirroring) and RAID 5 (striping with parity) are the most common forms of RAID.

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