Consider a single-platter disk with the following parameters: rotation speed: 7200 rpm; number of tracks on one side of platter: 30,000; number of sectors per track: 600; seek time: one ms for every hundred tracks traversed. Let the disk receive a request to access a random sector on a random track and assume the disk head starts at track 0.

These should be the question: a) What is the average seek time = 149.995 ms, b) average rotational latency = 4.16667ms , c) transfer time for a sector = 13.88us, and d) total average time to satisfy a request = 153.1805ms.

Step-by-step explanation:

A) average seek time.

Number of tracks transversed = 299.99ms

Seek time to access  the track = 0ms

= (0+299.99)/2 ==> 149.995ms

B) average rotational latency.

Rotation speed = 7,200rpm

rotation time = 60 / 7,200 = 0.008333s/rev

Rotational latency = 0.008333/2 = 0.004166sec

= 4.16667ms

C) Transfer time for a sector

at 7200rpm, a rev = 60 / 7200 = 0.00833s :    8.33ms

transfer time one sector = 8.333/600 ms

                                         = 0.01388ms  => 13.88us

D) average time to satisfy request

149 + 4.16667 + 0.013888

153.1805ms

false

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