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Examples of Disk Scheduling Algorithms

• Work Queue: 23, 89, 132, 42, 187
  
• there are 200 cylinders numbered from 0 - 199
  
• the diskhead stars at number 100

1. FCFS
   

   total time is estimated by total arm motion
   

2. SSTF
   

3. SCAN
   • assume we are going inwards (i.e., towards 0)

4. LOOK
   • reduce variance compared to SCAN

5. C-SCAN

6. C-LOOK

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Howard Hamilton
Wed Feb 2 10:00:00 CST 2000