High Availability Theoretical Basics - Schneider Electric
High Availability Theoretical Basics - Schneider Electric
High Availability Theoretical Basics - Schneider Electric
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The System Reliability, over a 1,000- hour mission, is:<br />
<strong>High</strong> <strong>Availability</strong> <strong>Theoretical</strong> <strong>Basics</strong><br />
n<br />
λ<br />
S<br />
= ∑ λ<br />
i 1<br />
i<br />
= λ<br />
1<br />
+ λ<br />
=<br />
2<br />
= 120 x 10 -6 + 180 x 10 -6 = 300 x 10 -6 = 0.3 x 10 -3 h -1<br />
−λ<br />
3 x 103<br />
S<br />
t − 0.3 x 10−<br />
− 0.3<br />
R S(1000<br />
h) = e = e<br />
= e = 0.7408<br />
Thus the targeted system Reliability is 74.08%<br />
<strong>Availability</strong><br />
Serial system <strong>Availability</strong> is equal to the product of the individual elements’<br />
Availabilities.<br />
A S<br />
=<br />
A1<br />
. A2<br />
. A3<br />
.... .An<br />
where: As= system (asymptotic) availability<br />
n<br />
= ∏ Ai<br />
i=<br />
1<br />
Ai = Individual element (asymptotic) availability<br />
n = Total number of elements on the serial system<br />
21
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