Operating Systems - Disk Scheduling - SSTF, SCAN, C-SCAN
In a system with highly skewed request distribution clustered near one end of the disk, which disk scheduling algorithm would minimize starvation and why?
In a system with highly skewed request distribution clustered near one end of the disk, which disk scheduling algorithm would minimize starvation and why?
hard⚖️ Approach Comparison Q8 of Q15
Step-by-Step Solution
Solution:
Step 1: Analyze skewed request distribution
Requests clustered near one end can cause starvation in SSTF if head stays near cluster.Step 2: Compare SCAN and C-SCAN
SCAN reverses direction, possibly delaying requests at far end; C-SCAN moves in one direction and jumps back, ensuring fairness.Step 3: Identify algorithm minimizing starvation
C-SCAN provides uniform wait times by servicing requests in a circular manner.Final Answer:
Option D -> Option DQuick Check:
C-SCAN's circular scan prevents starvation in skewed distributions [OK]
Quick Trick: C-SCAN's circular movement ensures fairness in skewed loads [OK]
Common Mistakes:
MISTAKES- Assuming SSTF prevents starvation
- Confusing SCAN's reversal with uniform wait
Trap Explanation:
PITFALL- Candidates often overlook C-SCAN's fairness advantage in skewed request patterns.
Interviewer Note:
CONTEXT- Tests ability to apply algorithms to non-uniform real-world scenarios.
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