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 efficient than RAID 3?

RAID 3, RAID 4, and RAID 5 all use parity system to protect blocks of data. Specifically, 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.

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New Data DO' 8 DO 1. Read 2. Read 3. Read D1 D2 D3 DO' 4. Write D1 +) XOR D2 D3 P P' 5. Write New Data 1. Read DO' DO D1 + XOR DO' 3. Write D1 D2 D3 +XOR D2 D3 2. Read P P 4. Write