Operating Systems - Disk Scheduling - SSTF, SCAN, C-SCAN
In which scenario is the SSTF (Shortest Seek Time First) disk scheduling algorithm most appropriate compared to SCAN or C-SCAN?
In which scenario is the SSTF (Shortest Seek Time First) disk scheduling algorithm most appropriate compared to SCAN or C-SCAN?
easy🔍 Pattern Recognition Q11 of Q15
Step-by-Step Solution
Step 1: Understand SSTF's goal
SSTF selects the closest request to the current head position to minimize seek time.Step 2: Consider starvation risk
SSTF can cause starvation for requests far from the current head position because it always picks the nearest request.Step 3: Compare with SCAN and C-SCAN
SCAN and C-SCAN move the head in a fixed direction to provide fairness and avoid starvation, sacrificing some seek time efficiency.Final Answer:
Option A -> Option AQuick Check:
When minimizing average seek time is the highest priority and starvation is acceptable correctly identifies SSTF's strength and its tradeoff with starvation risk.
Quick Trick: SSTF = fastest seek but can starve distant requests
Common Mistakes:
MISTAKES- Assuming SSTF always avoids starvation
- Believing SCAN/C-SCAN minimize seek time better than SSTF
- Confusing uniform distribution with SSTF suitability
Trap Explanation:
PITFALL- Options B and D describe SCAN/C-SCAN properties, tempting candidates who confuse fairness with seek time optimization. Option C is plausible but SSTF is not specifically designed for uniform heavy workloads.
Interviewer Note:
CONTEXT- Tests candidate's ability to match disk scheduling algorithms to workload priorities and understand trade-offs.
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