# Operating System - I/o System

6:

Disk requests come to a disk driver for cylinders 10, 22, 20, 2, 40, 6 and 38, in that order at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms per cylinder.

The total seek time, if the disk arm scheduling algorithm is first-come-first-served is

 A. 360 ms B. 876 ms C. 850 ms D. 900 ms Answer Report Discuss Option: B Explanation : According to FCFS order serverd will be (20),10, 22, 20, 2, 40, 6 and 38 Seek time = 10+12+2+18+38+34+32 = 146 The disk drive has to traverse totally 146 cylinders (verify). So, seek time is 6 x 146 = 876 ms. Click on Discuss to view users comments. Kishore R said: (6:17pm on Friday 9th October 2015) disk drive is reading from cylinder 20,fcfs ,20 2 40 6 38 10 22=138seek time=138x6=824 I had some confusion Write your comments here:
7:

Disk requests come to a disk driver for cylinders 10, 22, 20, 2, 40, 6 and 38, in that order at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms per cylinder.

If the scheduling algorithm is the closest cylinder next, then the total seek time will be

 A. 360 ms B. 876 ms C. 850 ms D. 900 ms Answer Report Discuss Option: A Explanation : Click on Discuss to view users comments. Write your comments here:
8:

Disk sheduling involves deciding

 A. which disk should be accessed next B. the order in which disk access requests must be serviced C. the physical location where files should be accessed in the disk D. none of these Answer Report Discuss Option: B Explanation : Click on Discuss to view users comments. Write your comments here:
9:

Poor response time are caused by

 A. Process or busy B. High I/O rate C. High paging rates D. All of these Answer Report Discuss Option: D Explanation : Click on Discuss to view users comments. Write your comments here:
10:

A certain moving arm disk storage with one head has following specifications : Number of tracks I recording surface 100 Disk rotation speed 2400 rpm Track storage capacity= 62500 bits

The average latency time (assume the head can move from one track to another only by traversing the entire track) is

 A. 2.5 s B. 2.9 s C. 3.1 s D. 3.6 s Answer Report Discuss Option: A Explanation :  In 60 seconds, the disk rotates 2400 times. So it takes 25ms to rotate it one time. There are 200 tracks. On average, 100 tracks need to be traveresed to reach a specific track. So 25ms*100 tracks= 2.5s time is taken on average to reach a particular track    Click on Discuss to view users comments. Write your comments here:

Syllabus covered in this section is-

• Main functions of operating systems
• Memory Management- Virtual memory, paging, fragmentation
• Concurrent Processing: Mutual exclusion, Critical regions, locks and unlock.
• Scheduling: CPU scheduling. I/O scheduling, Resource scheduling
• Banker's algorithm for deadlock handling.

This Section covers Operating System Questions Answers .These questions can be used for the preparation of various competitive and academic exams like

• UGC NET Computer Science
• Pre PhD Entrance Exam
• DOEACC Exams
• Kendriya Vidyalaya Sangathan Entrance Exam
• GATE Computer Science
• Post Graduate Computer Science Test
•  PhD Entrance Exam
• Computer Engineering
• State Eligibility Test (SET)
• National Eligibility Test (NET)

Who can benefit

• Operating System Objective Questions Answers can be used by any student who is preparing for PhD entrance exam, pre PhD entrance exam, entrance exam or any other such exam.
• Any student who is preparing for DOEACC exams can also use Operating System questions answers for preparation of his exams.
• Operating System mcq can be useful for the students who are pursuing any undergraduate or post graduate degree in computer science like BE, ME , Btech, Mtech, .BSc, MSc, BCA, MCA, BS, MS  or any other such degree
• Operating System mcq with answers and explanation can also be useful for the students who are preparing for any competitive exam or recruitment exams like GATE Computer Science, UGC NET Computer Science, Kendriya Vidyalaya Sangathan PGT exam, PSU, IES or any other such exam.
• Operating System multiple choice questions answers  can also be used by any candidate who wants to gain credits in Operating System in BS Computer science or MS Computer science,