Bissoy.com
Doctors Medicines MCQs Q&A

Consider a disk sequence with 100 cylinders. The request to access the cylinder occur in the following sequence : 4, 34, 10, 7, 19, 73, 2, 15, 6, 20 Assuming that the head is currently at cylinder 50, what is the time taken to satisfy all requests if it takes 2 ms to move from one cylinder to adjacent one and shortest seek time first policy is

Consider a disk sequence with 100 cylinders. The request to access the cylinder occur in the following sequence : 4, 34, 10, 7, 19, 73, 2, 15, 6, 20 Assuming that the head is currently at cylinder 50, what is the time taken to satisfy all requests if it takes 2 ms to move from one cylinder to adjacent one and shortest seek time first policy is Correct Answer 238

Disk scheduling Algorithm: shortest seek time first

Disk queue request: 4, 34, 10, 7, 19, 73, 2, 15, 6, 20

Ascending order: 2, 4, 6, 7, 10, 15, 19, 20, 34, 73

one head movement takes 2 milliseconds.

Initial head is 50th cylinder

[ alt="F1 R.S. N.J. 17.09.2019 D1" src="//storage.googleapis.com/tb-img/production/19/09/F1_R.S._N.J._17.09.2019_D1.png" style="width: 308px; height: 161px;">

Calculation:

Total head movement = |50 – 2| + |2 – 73|  = 48 +71 = 119

Total time = 119 × 2 = 238 milliseconds 

Related Questions

Consider a disk system having 60 cylinders. Disk requests are received by a disk drive for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. Assuming the disk head is currently at cylinder 20, what is the time taken to satisfy all the requests if it takes 2 milliseconds to move from one cylinder to an adjacent one and Shortest Seek Time First (SSTF) algorithm is used ?
Consider a disk system with 100 cylinders. The request to access the cylinders occur in the following sequences 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 time first algorithm is used
Consider the following five disk access requests of the form (request id, cylinder number) that are present in the disk scheduler queue at a given time. (P, 155), (Q, 85), (R, 110), (S, 30), (T, 115) Assume the head is positioned at cylinder 100. The scheduler follows Shortest Seek Time First scheduling to service the requests. Which one of the following statements is FALSE?
Disk requests come to a disk driver for cylinders in the order 10, 22, 20, 2, 40, 6 and 38, at a time when the disk drive is reading from cylinder 20. The seek time is 6 ms/cylinder. The total seek time, if the disk arm scheduling algorithms is first-come-first-served is
Let disk request come to a disk driver for cylinders in the order 10, 22, 20, 2, 40, 6 and 38, at the time when the disk driver is reading from cylinder 20. If the seek time is 6 ms per cylinder, then the total seek time for the disk arm scheduling time algorithm (FCFS - First Come First Serve) is:
Consider a disk queue with requests for I/O to blocks on cylinders. 98 183 37 122 14 124 65 67 Considering SSTF (shortest seek time first) scheduling, the total number of head movements is, if the disk head is initially at 53 is?
In making decisions about important questions, it is desirable to be able to distinguish between strong and weak arguments. Strong arguments are those, which are both important and directly related to the question. Weak arguments are those, which are of minor importance and also may not be directly related to the question or may be related to a trivial aspect of the question. The questions below are followed by two arguments each numbered I and II. You have to decide which of the two arguments is the strong argument and which is the weak argument. Statement: Should the Indian Government withdraw the subsidies on LPG cylinders considering a portion of the population can afford to buy unsubsidised cylinders? Arguments: Yes. Subsidising cylinders leads to its misuse. By not giving subsidies on cylinders, the Government can save a part of its income and spend it on other more productive uses. No. Withdrawing subsidies on cylinders would make them too expensive for the poor and the middle class income groups and they would eventually turn to unsustainable means for household uses leading to pollution and ill health.
Consider a disk queue with requests for I/O to blocks on cylinders. 98 183 37 122 14 124 65 67 Considering FCFS (first cum first served) scheduling, the total number of head movements is, if the disk head is initially at 53 is?
Consider a hard disk with 16 recording surfaces (0-15) having 16384 cylinders (0-16383) and each cylinder contains 64 sectors (0-63). Data storage capacity in each sector is 512 bytes. Data are organized cylinder-wise and the addressing format is . A file of size 42797 KB is stored in the disk and the starting disk location of the file is <1200, 9, 40>. What is the cylinder number of the last sector of the file, if it is stored in a contiguous manner?
Consider a hard disk with 16 recording surfaces (0-15) having 16384 cylinders (0-16383) and each cylinder contains 64 sectors(0-63). Data storage capacity in each sector is 512 bytes. Data are organized cyclinder-wise and the addressing format is . A file of size 42797KB is stored in the disk and the starting disk location of the file is <1200,9,40>. What is cylinder number of the last sector of the file, if it is stored in a contiguous manner?