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Recent questions tagged disk-scheduling

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61

what is meant by disk block address
what is meant by disk block address ??

hem chandra joshi asked in Operating System Sep 23, 2017

by hem chandra joshi

1.8k views

2 votes

1 answer

62

Disk scheduling problem
disk requests come to disk driver for cylinder 10,22,20,2,40,6,X in that order at a time when the disk drive is reading from cylinder 20 the seek time is 6ms per cylinder if the total seek time 876ms under fcfs scheduling algorithum then what is the value of x??

aaru14 asked in Operating System Aug 23, 2017

by aaru14

1.3k views

1 vote

1 answer

63

made easy work book
the head of a movin disk with 100 tracks numbered 0 to 99 is serving a request at track 'x' if the requests of track 25, 76, 43,10,67 are served using fifo algo. then head movements are 194 the track 'x' initially served was.?

aaru14 asked in Operating System Aug 20, 2017

by aaru14

2.7k views

2 votes

1 answer

64

Self Doubt
Order the following Disk Scheduling Algorithm on the basis of throughput FCFS, SCAN, C-SCAN, SSTF, LOOK, C-LOOK.

akb1115 asked in Operating System Aug 9, 2017

587 views

4 votes

2 answers

65

ISRO2017-66
Consider the disk system with 100 cylinders. The request to access the cylinders occur in the following sequence. 4, 37, 10,7,19,73,2,15,6,20 Assuming the head is currently at cylinder 50 what is the time taken to satisfy all requests if it takes 1 ms to move from one cylinder to adjacent one and shortest seek ime first algorithm is used. 95 ms 119 ms 233 ms 276 ms

sh!va asked in Operating System May 7, 2017

by sh!va

7.5k views

0 votes

1 answer

66

galvin
what basic information is stored with each disk sector?

iarnav asked in Operating System Apr 29, 2017

by iarnav

469 views

0 votes

2 answers

67

Is Disk Scheduling topic in OS is in syllabus?
Hello guys, I'm seeing a lot of questions on disk scheduling asked by various folks, but in GATE CS syllabus of OS - there's no topic as disk scheduling. So, please point me to the right direction where's the disk, sector seek time questions are coming?!

iarnav asked in Operating System Apr 10, 2017

by iarnav

1.4k views

2 votes

1 answer

68

Test by Bikram | Mock GATE | Test 3 | Question: 51
A disk has $200$ cylinders numbered $0$ to $199$ . The drive is currently serving a request at cylinder $53$, and the previous request was at cylinder $25$. The queue of pending requests, in $FIFO$ order, is --- ... the total distance the disk arm moves to satisfy all the pending requests for $C-LOOK$ disk-scheduling discipline is _____ cylinders.

Bikram asked in GATE Feb 9, 2017

by Bikram

748 views

1 vote

1 answer

69

Virtual Gate Operating system (Scan Algorithm)
Suppose that a disk drive has 5000 cylinders, numbered 0 to 4999. The drive is currently serving a request at cylinder 143, and the previous request was at cylinder 125. The queue of pending requests in order is: 86, 1470, 913, ... what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests using SCAN schedule?

Tendua asked in Operating System Jan 22, 2017

by Tendua

1.7k views

2 votes

2 answers

70

Operating System Concepts, 7th Edition, Q12.2
Suppose that a disk drive has 5,000 cylinders, numbered 0 to 4999. The drive is currently serving a request at cylinder 143, and the previous request was at cylinder 125. The queue of pending requests, in FIFO order, is: 86,1470, 913 ... , what is the total distance (in cylinders) that the disk arm moves to satisfy all the pending requests for C-SCAN?

ਜਗਮੀਤ asked in Operating System Jan 20, 2017

by ਜਗਮੀਤ

5.7k views

1 vote

2 answers

71

Test by Bikram | Mock GATE | Test 1 | Question: 40
The head of a moving head disk with $100$ tracks numbered $0$ to $99$ is serving a request at track $x$. if the requests of track $25, 76, 43, 10, 67$ are served using $FIFO$ algorithm, then total head movements are $194$. The track $x$ initially served was at ________.

Bikram asked in GATE Jan 16, 2017

by Bikram

1.7k views

4 votes

2 answers

72

testbook test series

asu asked in Operating System Jan 15, 2017

by asu

1.4k views

1 vote

6 answers

73

SSTF Disk Scheduling
My answer is 202 given 232

monty asked in Operating System Jan 6, 2017

by monty

1.9k views

2 votes

1 answer

74

Doubt in Circular-Look and Circular-Scan
In C-Look or in C-Scan when we take the circular move (from last to first), is this movement counted or not? After searching I found that: It should included: http://www2.cs.uregina.ca/~hamilton/courses/330/notes/io/node8. ... http://www.cs.iit.edu/~cs561/cs450/disksched/disksched.html I'm really confused. Please provide the reference of your solution.

target2017 asked in Operating System Dec 9, 2016

1.1k views

21 votes

2 answers

75

GATE CSE 1989 | Question: 4-xii
Disk requests come to 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 $6$ msec per cylinder. Compute the total seek time if the disk arm scheduling algorithm is. First come first served. Closest cylinder next.

makhdoom ghaya asked in Operating System Nov 30, 2016

by makhdoom ghaya

5.1k views

16 votes

2 answers

76

GATE CSE 1990 | Question: 9b
Assuming the current disk cylinder to be $50$ and the sequence for the cylinders to be $1, 36, 49, 65, 53, 12, 3, 20, 55, 16, 65$ and $78$ find the sequence of servicing using Shortest seek time first (SSTF) and Elevator disk scheduling policies.

makhdoom ghaya asked in Operating System Nov 24, 2016

by makhdoom ghaya

5.5k views

1 vote

1 answer

77

Self Doubt in Disk Scheduling
I am presenting here 2 doubts in the form of questions.Plz give proper explanation to these : Q1 : Out of the available disk scheduling algorithms , which can be considered as the best and most practical? Q2 : In CSCAN or CLOOK , we consider ... for those requests which are on the opposite side w.r.t. initial direction of head movement and hence not yet serviced ?

Habibkhan asked in Operating System Oct 31, 2016

967 views

1 vote

2 answers

78

MadeEasy Test Series: Operating System - Disk Scheduling

vaishali jhalani asked in Operating System Oct 11, 2016

by vaishali jhalani

528 views

2 votes

1 answer

79

Ace Gate practice Booklet (1116 Expected questions) Volume 2
Consider a disk with the following specification disk block size is 'S' bytes; Disk Block address id 'D' bits, Disk size is 'B' bytes. 'K' of the total blocks are in use. What is the total space consumption under free list and bit map methods ... b) (B(1+D) - DS)/S c) B/S + ((B-K)/S).D d) B/S + K.D

Manoj Majumdar asked in Operating System Oct 2, 2016

by Manoj Majumdar

4.8k views

0 votes

2 answers

80

GATE Overflow | Operating Systems | Test 1 | Question: 23
Consider an operating system capable of loading and executing a single sequential user process at a time. The disk main scheduling algorithm used is FCFS. If FCFS is replaced by SSTF claimed by the service provider to give 50% ... results, what is the expected improvement in the I/O performance of user programs? 50% 40% 25% no improvement

Bikram asked in Operating System Sep 3, 2016

by Bikram

611 views

6 votes

3 answers

81

UGC NET CSE | June 2011 | Part 2 | Question: 23
The number of disk accesses performed by insertion operation in B-tree of height $h$ is $0(1)$ $0(1gh)$ $0(h)$ None of these

makhdoom ghaya asked in Others Aug 23, 2016

by makhdoom ghaya

1.7k views

5 votes

2 answers

82

UGC NET CSE | June 2016 | Part 2 | Question: 38
If the Disk head is located initially at track 32, find the number of disk moves required with FCFS scheduling criteria if the disk queue of I/O blocks requests are 98, 37, 14, 124, 65, 67 320 322 321 319

go_editor asked in Operating System Aug 16, 2016

19.7k views

3 votes

2 answers

83

UGC NET CSE | Junet 2015 | Part 2 | Question: 36
A disk drive has $100$ cylinders, numbered $0$ to $99$. Disk requests come to the disk driver for cylinders $12, 26, 24, 4, 42, 8$ and $50$ in that order. The driver is currently serving a request at a cylinder $24$. A seek takes $6$ ... seek time is needed for shortest seek time first (SSTF) algorithm? $0.984$ sec $0.396$ sec $0.738$ sec $0.42$ sec

go_editor asked in Operating System Jul 30, 2016

9.7k views

2 votes

1 answer

84

UGC NET CSE | December 2014 | Part 3 | Question: 51
Consider an imaginary disk with $40$ cylinders. A request come to read a block on cylinder $11$. While the seek to cylinder $11$ is in progress, new requests come in for cylinders $1, 36, 16, 34, 9$ and $12$ in that order. The number of arm motions using shortest seek first algorithm is $111$ $112$ $60$ $61$

makhdoom ghaya asked in Operating System Jul 30, 2016

by makhdoom ghaya

3.2k views

5 votes

1 answer

85

UGC NET CSE | December 2013 | Part 2 | Question: 48
Consider a disk queue with request for input/output to block cylinders 98, 183, 37, 122, 14, 124, 65, 67 in that order. Assume that disk head is initially positioned at cylinder 53 and moving towards cylinder number 0. ... ) and SCAN algorithms are respectively 236 and 252 cylinders 640 and 236 cylinders 235 and 640 cylinders 235 and 252 cylinders

go_editor asked in Operating System Jul 26, 2016

21.3k views

5 votes

1 answer

86

UGC NET CSE | September 2013 | Part 2 | Question: 46
Consider the input/output (I/O) request made at different instants of time directed at a hypothetical disk having $200$ tracks as given in the following table $:$ ... : $144$ and $123$ milliseconds $143$ and $123$ milliseconds $149$ and $124$ milliseconds $256$ and $186$ milliseconds

go_editor asked in Operating System Jul 21, 2016

4.1k views

2 votes

2 answers

87

UGC NET CSE | December 2012 | Part 2 | Question: 5 UGCNET-June2013-II: 47
If the disk head is located initially at 32, find the number of disk moves required with FCFS if the disk queue of I/O blocks requests are 98. 37, 14, 124, 65, 67. 239 310 321 325

go_editor asked in Operating System Jul 8, 2016

3.6k views

5 votes

4 answers

88

UGC NET CSE | June 2012 | Part 3 | Question: 74
On a disk with 1000 cylinders (0 to 999) find the number of tracks, the disk arm must move to satisfy all the requests in the disk queue. Assume the last request service was at track 345 and the head is moving toward track 0. ... order contains requests for the following tracks: 123, 874, 692, 475, 105, 376 (Assume scan algorithm) 2013 1219 1967 1507

go_editor asked in Operating System Jul 8, 2016

12.3k views

0 votes

1 answer

89

MadeEasy Test Series: Operating System - Disk Scheduling
Consider the following disk request sequence for a disk with 100 tracks. 98, 183, 37, 122, 14, 124, 65, 67 Head pointer starting at 53 (current position of R/W heads).Find the number of head movements in cylinders using SSTF scheduling.

Jitendra Verma asked in Operating System Mar 16, 2016

by Jitendra Verma

3.3k views

0 votes

2 answers

90

MadeEasy Test Series: Operating System - Disk Scheduling
Consider the following disk request sequence for a disk with 100 tracks. 98, 183, 37, 122, 14, 124, 65, 65, 67 Head pointer starting at 53 (current position of R/W heads) and moving in left direction.Find the number of head movements in cylinders using SCAN scheduling.

Jitendra Verma asked in Operating System Mar 16, 2016

by Jitendra Verma

2.2k views

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