1. Disk-access time = (seek time) + (rotational delay) + (date transfer time).

a) How is each component of the disk-access time effected by the disk's RPM (revolutions per minute)?

b) How is each component of the disk-access time effected by the sector size?

2. Suppose we have a 5 disk RAID 5 (block-level distributed parity) array.

a) If Disk 0 crashes, reconstruct the first three bits of block 0. Assume even parity is being used.

b) Assume that Disk 0 has crashed. If you write a new block of data starting with bits 0 1 1 ... to Block 3, then can Blocks 5 and 6 be read at the same time as the write for Block 3 is occurring? (Justify your answer)

3. Suppose we have an 5 disk RAID array with each disk having a 100 MB/sec data transfer rate. Complete the following table assuming none of the disks are faulty.

RAID Level Maximum number of concurrent, independent READs Maximum number of concurrent, independent WRITEs Data Transfer Rate for a single large READ
RAID 1

(Mirroring with large strips)

     
RAID 3

(bit-interleaved parity)

     
RAID 5 (block-level distributed parity)