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A disk drive has 5000 cylinders,  numbered 0 to 4999.  The drive is serving a

request at cylinder 143 currently  and the previous  request was at 125. The disk I/O queue, in FIFO order, is

        86, 1470, 913, 1774, 948, 1509, 1022, 1750, 130

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?
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The SCAN schedule is 143, 913, 948, 1022, 1470, 1509, 1750, 1774, 4999, 130, 86.

The total seek distance is 9769.
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SCAN algorithm progresses in one direction till the very end and then changes direction and serves other requests left.

PS:

Ans:9769 

. There is a mistake in writing answer in the attached image

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