Which RAID Level often implements a one-for-one disk to disk ratio?

A.
RAID Level 1

B.
RAID Level 0

C.
RAID Level 2

D.
RAID Level 5

Explanation:
RAID Level 1, disk mirroring, uses a one-for-one setup, where data are written to two drives at once. If one
drive fails, the other drive has the exact same data available.
Incorrect Answers:
B: RAID Level 0 uses data striped over several drives, not just two drives. There is not one-to-one disk ratio.
C: RAID Level 2 uses data striped over several drives, not just two drives. There is not one-to-one disk ratio.
D: RAID Level 5 does not use a one-to-one disk ratio.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, New York, 2013, p. 1270