請問有人可以告訴我這兩個題目在問什麼並解答嗎?

2009-03-22 9:55 am

1.If a computer issues 30 network requests per second and each re-quest is on average 64 kb,will a 100 mbit ethernet link be sufficient?

2.In a magnetic disk, the disks containing the data are constantly rotating. On average it should
take half a revolution for the desired data on the disk to spin under the read/write head. Assuming
that the disk is rotating at 7200 revo-lutions per minute(RPM),what is the average time for the
data to rotate under the disk head? What is the average time if the disk is spinning at 10000
revolutions per minute?

回答 (1)

bean_bottom_2

2009-03-23 7:09 am

✔ 最佳答案

1. for 30 requests with an average of 64kb, you will need a bandwidth of 30 per s X 64kb / 1024 = 1.875 Mbps. Given the fact that a 100Mbps ethernet link will have a throughput of about 40Mbps. This should work out fine.

2. If the disk is rotating at 7200rpm and it will take 1/2 revolution to get to the data, the average time taken for data to reach under the head will be 60 / 7200 X 1/2 X 1000 ms = 4.167 ms

For a disk with rotation of 10000rpm, the average time will be 60 /10000 X 1/2 X 1000 ms = 3ms (or you can just use ratio of 7200 to 10000).

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