Which of the following RAID (Redundant Array of Independent Disks) implementations provides fault tolerance but not improved performance?

A.
RAID-0

B.
RAID-1

C.
RAID-3

D.
RAID-5

Explanation:
RAID-1 is a disk fault tolerance system in which two disks are exact mirrors of each other. Should the one disk fail, the system would still be operable, the failed disk can be replaced, and the mirror rebuilt. However, this does not improve performance.
Incorrect Answers:
A: RAID-0 is not a fault tolerance system. It uses striping on all disks to improve performance but does not use parity and thus does not provide fault tolerance.
C: RAID-3 uses striping and parity on a dedicated drive for improved performance as well as fault tolerance.
D: RAID-5 uses striping and parity drive to provide fault tolerance for improved performance as well as fault tolerance.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 184-192.

David Groth and Toby Skandier, Network+ Study Guide (4th Edition), Sybex, Alameda CA, 2005, pp. 381-382.