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Disk requests come in to the disk driver for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order

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1. Disk requests come in to the disk driver for cylinders 10, 22, 20, 2, 40, 6, and 38, in that order. A seek takes 6 msec per cylinder. How much seek time is needed for the following (In all cases, the arm is initially at cylinder 20): (30%)
   • First-come, first served
   • Closest cylinder next
   • Elevator algorithm (initially moving upward)
     
      
2. D escribe two advantages and two disadvantages of thin client computing. (20%) 
   
    
3. In which of the four I/O software layers is each of the following done: (30%)
   • Computing the track, sector, and head for a disk read
   • Writing commands to the device registers
   • Checking the see if the user is permitted to use the device
   • Converting binary integers to ASCII for printing
     
      
4. RAID level 3 is able to correct single-bit errors using only one parity drive. What is the point of RAID level 2? After all, it also can only correct one error and takes more drives to do so. (20%)