Download CS 471: Operating System Concepts Exam II - Fall 2005 - Prof. Ravi Mukkamala and more Exams Operating Systems in PDF only on Docsity!
CS 471: Operating System Concepts
Fall 2005
Examination II
Points: 150
November 12, 2005
Time: 8:30-11:30 AM
CLOSED BOOK
Turning in this exam under your name confirms your continued support for the
honor code of Old Dominion University and further indicates that you have
neither received nor given assistance in completing it.
Name: _________________________________ UID: ______________________
CS Unix ID: ___________@cs.odu.edu
Question # Points
Maximum Obtained
Total 150
YOU MUST WRITE ONLY IN THE SPACE PROVIDED. WORK
OUTSIDE THIS SPACE WILL NOT BE GRADED.
USE A BLACK PEN TO ANSWER THE QUESTIONS
DO NOT WRITE HERE
DO NOT WRITE HERE
Question 2.
(a) On a disk, space is allocated using indexed allocation. If a file F1 is allocated the following blocks (in that order), show the contents of the directory for F1 and the index block for F (located in block 200). Blocks allocated to f1: 15, 9, 210, 13, 35, 27, 96, 230 WORK AREA
(b) Answer question (a) assuming shortest-job-first scheduling with preemption.
(b) In the same system, free space on the disk is managed using link list. If the following blocks are the only blocks that are free, show how the free space will be represented. 23, 45, 78, 190, 245, 997, 1234
WORK AREA:
Question 3.
(a) Suppose that a disk drive has 8000 cylinders, numbered 0..7999. The drive is currently serving a request at cylinder 250, and the previous request was at cylinder 320. The queue of pending requests, in FIFO order, is: 500, 200, 750, 50, 4000 Starting from the current head position, what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests for SCAN disk-scheduling algorithm WORK AREA:
(b) Answer (a) above assuming SSTF (Shortest seek time first) disk-scheduling algorithm.
WORK AREA:
DO NOT WRITE HERE
DO NOT WRITE HERE
Question 5.
(a) Explain how cache consistency is maintained in NFS and AFS file servers. WORK AREA:
(b) 100, 150, 200 are the timestamps of processes P1, P2, and P3, respectively. Currently, resource R1 is held by P2. Both P1 and P3 (in that order) also made requests for R1. Discuss the outcome of the requests from P1 and P3 under (i) Wait-die scheme (ii) Wound-wait scheme. WORK AREA:
