MTTF = 10^9 / 200 =
= 5 * 10^6
If it takes two days to get the system running again, what is the availability of the system?
Availability = MTTF / ( MTTF + MTTR)
= 5 * 10^6 / (5 * 10^6 + 48)
= 99.999%
4) The Cost of Reliability (and Failure) in Web Servers
Imagine that the government, to cut costs, is going to build a supercomputer out of the cheap processor system in Exercise 3 above rather than a special purpose reliable system. What is the MTTF for a system with 100 processors? Assume that if one fails, they all fail.
FIT = 100 * 200
= 20,000
MTTF = 10^9 / 20,000
= 5 * 10^4
5) Performance
Your company has just bought a new dual Pentium processor, and you have been tasked with optimizing your software for this processor. You will run two applications on this dual Pentium, but the resource requirements are not equal. The first application needs 75% of the resources, and the other only 25% of the resources.
Given that 60% of the first application is parallelizable, how much speedup would you achieve with that application if run in isolation?
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