The Megatron 777 disk has the following characteristics 1 Th
The Megatron 777 disk has the following characteristics:
1. There are ten surfaces, with 100,000 tracks each.
2. Tracks hold an average of 1000 sectors of 1024 btyes each.
3. 20% of each track is used for gaps.
4. The disk rotates at 10,000 rpm.
5. The time it takes the head to move n tracks is 1 + 0.0002n milliseconds.
Answer the following questions about the Megatron 777.
a) What is the capacity of the disk?
b) If tracks are locatd on the outer inch of a 3.5-inch-diamter surface, what is the average density of bits in the sectors of a track?
c) What is the maximum seek time?
d) What is the maximum rotational latency?
e) If a block is 65,546 bytes (i.e., 64 sectors), what is the transfer time of a block?
f) What is the average seek time?
g) What is the average rotational latency?
Solution
a) The disk has 10 * 10, 0000 = 100, 0000 tracks. . Thus, the capacity is 100, 0000 *1000*1024
b) Substitute 10,000 for n in the formula (1 + 0.0002n) = 1+ 2/10000*1000000 = 21ms
c) Since the disk rotates at 10,000 rpm, it takes 60/10000 of minute or 6 milliseconds.
d) 64 sectors with 63 gaps and 1000 sector with 1000 gap
Degrees = (64/1000 *10% + 63/1000 * 90%). * 360 = 23.004 degree
Time =. 23.004/360 * 10% = 63.9 ms
e) The average seeks time. = 1 + 0.0002 * (100000/2) = 11 ms
f) Average rotational delay = max rotational latency /2 = 5ms
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