Level 0

Min # of drives: 2

Data striping without redundancy

Level 1

Min # of drives: 2

Disk mirroring.

Level 2

Min # of drives: 2

Error-correcting code.

Level 3

Min # of drives: 3

Byte level data striping with dedicated parity.

Level 4

Min # of drives: 3

Block level data striping with dedicated parity.

Level 5

Min # of drives: 3

Combination of data striping and parity.

Level 6

Min # of drives: 4

Independent data disks with double parity.

Raid 0+1

Min # of drives: 4

Combination of data striping and mirroring.

Level 10

Min # of drives: 4 (must be even number)

Mirrored set in a striped set.