1. The read access delay for an I/O system is defined as the time required for t

Question

1. The read access delay for an I/O system is defined as the time required for the device to acquire the requested data and prepare to start transmitting the data. The data transfer rate for an I/O device is defined as the number of bytes per second that it can transmit. Suppose that there are two different I/O systems A and B. System A has a data transfer rate of 5120 bytes per second and has an access delay of 5 seconds. System B has a data transfer rate of 3072 bytes per second and has an access delay of 4 seconds.

(a) How long will each system require to complete a 3145728-byte I/O request?

(b) It is observed that for an I/O request of size N bytes, the two systems require the same amount of time to complete the request. What value is N?

Explanation / Answer

Anyway, this is just simple math. Divide the 3145728 bytes by the transfer rate, and then add the access delay.

System A has a data transfer rate of 5120 bytes per second and has an access delay of 5 seconds.

so 3145728 /5120 = 614.4 +access delay(5 seconds)=619.4

whereas

System B has a data transfer rate of 3072 bytes per second and has an access delay of 4 seconds.

so 3145728 /3072 = 1024+access delay(4)= 1028

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