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GATE CSE 2020 Q45: False statement about an SSTF disk schedule from cylinder 100

Question

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?

Try it: multiple choice: exactly one correct option

Select one option
Wrong answer costs 2/3 mark in GATE.
Show answer and explanation

Answer: B (official GATE 2020 final answer key)

Concept used: SSTF always serves the pending request nearest to the current head position.

First step: From 100 the nearest is R (110), then T (115); from 115 compare Q (85, distance 30) with P (155, distance 40), and continue.

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Source: official GATE 2020 CS question paper and final answer key, organised by IIT Delhi. Question paper · Answer key

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