Exercise 6.15 RAID 3, RAID 4, and RAID 5 all use parity system to protect blocks of data. Specifi cally, a parity block is associated with a collection of data blocks. Each row in the following table shows the values of the data and parity blocks, as described in Figure 6.13.

New D0 D0 D1 D2 D3 P

a. FEFE 00FF A387 F345 FF00 4582

b. AB9C F457 0098 00FF 2FFF A387 6.15.1 [10] <6.9> Calculate the new parity P’ for RAID 3.

6.15.2 [10] <6.9> Calculate the new parity P’ for RAID 4.

6.15.3 [5] <6.9> Is RAID 3 or RAID 4 more effi cient? Are there reasons why RAID 3 would be preferable to RAID 4?

6.15.4 [5] <6.9> RAID 4 and RAID 5 use roughly the same mechanism to calculate and store parity for data blocks. How does RAID 5 differ from RAID 4 and for what applications would RAID 5 be more effi cient?

6.15.5 [5] <6.9> RAID 4 and RAID 5 speed improvements grow with respect to RAID 3 as the size of the protected block grows. Why is this the case? Is there a situation where RAID 4 and RAID 5 would be no more effi cient than RAID 3?