Your customer wants to guard against the simultaneous loss of any two disk drives in his RAID
array. Which RAID level can be used to accomplish this?
A.
RAID 1
B.
RAID 3
C.
RAID 5
D.
RAID 6
Explanation:
Industry Standard Architecture – Student Guide 1 – Page 261
RAID 6 – Advanced data guarding
RAID 6, also known as Advanced Data Guarding (ADG), provides high fault tolerance. It
distributes two sets of parity data protecting against two drive failures.
As the graphic shows, parity (P) is written twice for each piece of data (D). These two sets are
different, and each set occupies a capacity equivalent to that of one of the constituent drives.
Answer is D.
RAID 6, also known as double-parity RAID, uses two parity stripes on each disk. It allows for two disk failures within the RAID set before any data is lost.
This configuration offers very high fault- and drive-failure tolerance. It is used for environments that need long data retention periods, such as archiving. One disadvantage in using RAID 6 is that each set of parities must be calculated separately, which slows write performance. Implementing RAID 6 is also more expensive because of the two extra disks required for parity.
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