GATE 2014 CS (CS1) – Question 29
A disk has cylinders 0–200. The arm is at 100 with queued requests 30,85,90,100,105,110,135,145. With Shortest-Seek-Time-First scheduling, how many requests are serviced before the request for cylinder 90?
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Correct answer: 3 to 3
Explanation
Starting at100, service the queued100 request first. The nearest next request is105, followed by110. Cylinder90 is then20away, nearer than135 at25away, and is selected next. Thus **three requests** have been serviced before90; the90 request itself is not counted.