please show all work (3) 6. A hard disk is spinning at 5400 RPM. Assume the read
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please show all work
(3) 6. A hard disk is spinning at 5400 RPM. Assume the read/write heads are already positioned at the desired cylinder. What are the best case, worst case, and average rotational delays to arrive at the desired sector for reading or writing data? (Show all work.) A small hard disk has five double-sided platters, each with its own pair of read/write heads. It is formatted with 512-byte sectors. It has 1024 tracks per platter and there are 480 sectors per track. What is the storage capacity of the disk? (Show all work) (4) 7.Explanation / Answer
6.
Worst case rotational latency is when disk has perform a full rotation which can be give by below formula
60 *1000)/(rev/min) = ms/rev
60000/5400 = 11.11 ms
Best case latency is when the required data is just read/write head so there is no rotation required in that case the latency is 0
Average case latency is average of above two cases which is (11.11+0)/2 = 5.555 ms
7.
Size of one sector is 512 byte
There is 480 sector per track.
So, the size of a track is 480 * 512 = 245760 bytes
Again, there is 1024 tracks per platter.
So, the size of a platter is 1024 * 245760 = 251658240 bytes (please see explanation at the end)
There is 5 platter in the disk
So, the total size of the dis is 251658240 * 5 = 1258291200 bytes = 1.171875 GB
Please note, this question doesn't clearly tell that if the platter has 1024 tracks on a each side or it has total 1024 track on both side. If it contains 1024 tracks in each side then the size of hard disk gets doubled accordingly.
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