Question

In a server farm such as that used by Amazon or eBay, a single failure does not cause the entire system to crash. Instead, it will reduce the number of requests that can be satisfied at any one time. If a company has 10,000 computers, each with a MTTF of 35 days, and it experiences catastrophic failure only if 1/3 of the computers fail, what is the MTTF for the system? (Assume that computers are not repaired.)

Answer 1

Answer:12 days

Step-by-step explanation:

Mean time to failure is given by

MTTF=
`(Total working hours of running)/(Total no. of units)`

Let's say N is the average amount of time system runs until
`(1)/(3)` computer fail

MTTF of each computer =35

35=
`(n\cdot 10,000)/(10,000\cdot (1)/(3))`

`35=N\cdot 3`

N=
`(35)/(3)=11.667\approx 12days`