Homework #4
| Assigned: | November 12th |
| Due: | Friday, November 21st at 11:59 PM |
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All work on this homework must be your own. Please read (and follow!) the academic honesty policy for this class.
- Problem 4.33 from the text (page 266).
- Problem 4.35 from the text (page 267).
- Problem 5.17 from the text (page 375).
- A disk has 40,000 cylinders, 2 surfaces, and 2 MB per track. It rotates at 7200 RPM, and average seek time is 7 ms.
- What is the capacity of this disk?
- How long does it take to read a 4 KB sector? Assume a request is an average seek followed by an average rotation, and compute the transfer size using the rotation rate and track size.
- How many requests (from part b) can this disk handle per second?
- Disk requests arrive to the disk driver for cylinders 1712, 605,
4183, 4057, 9541, 6779, and 1098 in that order. The disk has a total
of 20,000 cylinders, and a seek requires (0.0813 * sqrt(cylinders-1)
+ 0.000475* (cylinders-1)+0.5) milliseconds. For example, a seek of
from cylinder 800 to cylinder 900 (100 cylinders) would require (0.0813*sqrt(99)+0.000475*99+0.5)
= 1.36 ms. The head is currently at cylinder 2000 and moving towards
higher-numbered cylinders. Find the total number of cylinders crossed
and total seek time required for each of:
- First-come, first-served
- Shortest seek distance first
- LOOK (don't seek to the end of the disk)
- C-LOOK (don't seek to the end of the disk)
- Problem 5.25 in the text (page 376).
- Problem 5.45 in the text (page 378).
Last updated 12 Nov 2003 by Ethan L. Miller (elm@ucsc.edu)