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ISM question on disk utilization
Can someone explain how these calculations are done ?
Consider a disk I/O system in which an I/O request arrives at a rate of 100 IOPS and the service time is 4 ms.
What is the utilization?
A. 40%
B. 10%
C. 80%
D. 4%
Answer:
A
Anonymous
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May 17th, 2011 21:00
Formula for this problem is:
U = Rs/Ra
Where: U is utilization, Rs is the service time, and Ra is the average inter-arrival time.
Given:
I/O request arrives = a = 100 IOPS
service time = Rs = 4 ms
Ra = 1/a = 10 ms
U = Rs/Ra = 4/10 = 0.8 or 40 %
Shawky1
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May 18th, 2011 08:00
Rs: service time is 4ms = 4/1000 sec
a: arrive rate of 100 IOPS
U= a * Rs
=100 * (4/1000) = 0.4
So the Utilization percentage would be 40%