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Hard Disk Access

A certain hard disk has 480 cylinders, 16 tracks, and 32 sectors of 512 bytes each. It spins at 4800 revolutions per minute, and has an adjacent cylinder seek time of 80 msec, and a max seek time of 100 msec. Switching between tracks in the same cylinder is instantaneous. Use this information to answer the following 4 questions.
1. What is the total available storage capacity of the disk?
2. What is the minimum worst-case time required to read all the data on the disk, starting with the first track of the first cylinder, reading all the tracks in that cylinder, advancing to the next cylinder, etc.?
3. How much bandwidth (Mbytes/second) would a bus need to keep up with this drive at its maximum sustained data rate? Round your answer to three significant digits.
4. How large a buffer would be needed to allow a complete cylinder to be stored to permit reading or writing to occur at top speed?

Solution Preview

1. What is the total available storage capacity of the disk?
125,829,120 Bytes (= 480 * 16 * 32 * 512)

This is 120 MB

2. What is the minimum worst-case time required to read all the data on the disk, starting with the first track of the first cylinder, ...

Solution Summary

The following problem is resolved in this material.

A certain hard disk has 480 cylinders, 16 tracks, and 32 sectors of 512 bytes each. It spins at 4800 revolutions per minute, and has an adjacent cylinder seek time of 80 msec, and a max seek time of 100 msec. Switching between tracks in the same cylinder is instantaneous. Use this information to answer the following 4 questions.

1. What is the total available storage capacity of the disk?
2. What is the minimum worst-case time required to read all the data on the disk, starting with the first track of the first cylinder, reading all the tracks in that cylinder, advancing to the next cylinder, etc.?
3. How much bandwidth (Mbytes/second) would a bus need to keep up with this drive at its maximum sustained data rate? Round your answer to three significant digits.
4. How large a buffer would be needed to allow a complete cylinder to be stored to permit reading or writing to occur at top speed?

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