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Forum: Electrical & Computer Engineering :: Data Structures & Algorithms :: Disk Accessing  New Topic
Problem #4 Reply
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nak31 Problem #4 Mon 20 Apr 2009 8:22:00 PM
Student
Joined Tues 31 Mar 2009
Posts 511
The time needed to read data found on 4 consecutive tracks is 215ms. Given the disk is rotating at 5400 rpm, track-to-track seek time is 1.8ms, and the interleaving factor is 4. Find the disk access seek time.
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nak31 Mon 20 Apr 2009 8:23:00 PM
Student
Joined Tues 31 Mar 2009
Posts 511

Solution 4:

 

Rotational Delay is 0.5 * (1/frequency) = 0.5 * (60/5400)
                                                                        = 11.1/2 ms

First track= Seek time + Rotational delay + interleaving factor x time to read one track
                   =
seek time + 11.1/2 + 4 x 11.1
                   = seek time + 49.95 ms

Remaining  track = Track-to-track seek time + Rot. delay + int. factor x time to read one track
                                 
= 1.8 + 11.1/2 + 4 x 11.1
                                  = 51.75 ms.

Total time = time to read first track + 7* time to read remaining track
   215ms     = seek time + 49.95 + 3*51.75

 Seek time = 215 – 205.2 ms
                    = 9.8ms

 


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