Which RAID level concept is considered more expensive and is applied to servers to create what is commonly
known as server fault tolerance?

A.
RAID level 0

B.
RAID level 1

C.
RAID level 2

D.
RAID level 5

Explanation:
RAID level 1 is mirroring of drives. Data are written to two drives at once. 50% of the disks are used for fault
tolerance.
Incorrect Answers:
A: RAID level 0, data striping, provides no fault tolerance.
C: RAID Level 2 uses parity for fault tolerance, but is not used in production today.
D: RAID level 5 uses one parity bit for fault tolerance. With three drives, the minimum amount, 33% of the disks
are for fault tolerance.

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