MCS-041 Solved Assignment 2014-2015
Question 1: On a disk with 1000 cylinders, numbers 0 to 999, compute the number of tracks the disk arm must move to satisfy all the requests in the disk queue. Assume the last request serviced was at track 345 and head is moving to track 0. The queue in FIFO order contains requests for the following tracks: 123, 874,692, 475, 105, 376. Perform the computation for the following disk scheduling algorithms: (a) FIFO (b) SSTF (c) SCAN (d) LOOK
Solution:
(a) FIFO - 2013
The tracks traveled to will be 345,123,874,692,475,105
and 376 making the total distance 222+751+182+217+370+271=2013.
(b) SSTF-1298
The tracks traveled to will be 345,376,475 ,692,874, 123 and 105 making
the total distance 529+769=1298
(c) SCAN- 1219
The tracks traveled to will be 345,123,105,0,376,475,692 and 874
making the total distance 345+874 =1219
(d) LOOK-1009
The tracks traveled to will be 345,123,105,376,475, 692 and 874
making the total distance 240+769=1009
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