# hpca/sample-final/samplefinal2/problem6

Problem 6. 15 Points - Storage

A 12,000RPM disk drive has 2 platters, with 100,000 tracks per surface, 1,000 sectors

per tracks, and 512 data bytes per sector. Each sector also has a 128-bit error detection

code that can detect all errors in its sector but cannot correct any errors. The head takes

ten microseconds (a 100,000th

cylinder, and multi-cylinder movements are done at the same speed (100,000 cylinders

per second). The disk controller is very fast (assume zero latency for everything it does)

and the I/O bus has very large (assume infinite) bandwidth.

A) [2 point] How many heads does the disk drive have?

B) [3 points] Assuming that the disk controller and the drive itself are not servicing

any other requests, what is the worst-case time needed to read a sector from the

disk?

of a second) to move from one cylinder to an adjacent

C) [3 points] If we use two of these disk drives in a RAID0 configuration, and if the

array is full (it contains as much data as its capacity allows), what is the best-case

time needed to read all of the data stored in the array?

D) [3 points] If we use five of these disk drives in a RAID5 configuration, and if the

array is full (it contains as much data as its capacity allows), what is the best-case

time needed to read all of the data stored in the array?