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Consider a RAID Level 5 organi

[问答题]

Consider a RAID Level 5 organization comprising five disks, with the parity for sets of four blocks on four disks stored on the fifth disk. How
many blocks are accessed in order to perform the following?
a. A write of one block of data
b. A write of seven continuous blocks of data

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1) A write of one block of data requires the following: read of the parity block, read of the old data stored in the target block, computation of the new parity based on the differences between the new and old contents of the target block, and the write of the parity block and the target block.

2) Assume that the seven contiguous blocks begin at a four-block boundary. A write of seven contiguous blocks of data could be performed by writing the seven contiguous blocks, writing the parity block of the first four blocks, reading the eight block, computing the parity for the next set of four blocks and writing the corresponding parity block onto disk.

发表于 2018-03-23 21:55:27 回复(0)