Mailing List Archive

Mailing List: techdiver

Message Display

On Wed, 19 Jul 1995, Paul W. Smith wrote:

> > Now, add two more identical computers, any one of which can fully operate
> > the system.  The computer complexity has just increased by a factor of 3,
> > so the probability of a component failure has tripled.  However, since 3
> > simultaneous computer failures are required to bring the whole system
> > down, the probability of a system failure is the cube root of the
> > probability of a single computer failure (i.e., MUCH less -- assuming the
> > three computers are truly independant entities).
> 
> Golly, Batman- do you suppose that could apply to SCUBA sets, too?

My guess is that you, and almost everyone on this list, already applies
it to open-circuit SCUBA.  Here, I'll rephrase it:

Take a scuba tank. Now, add a Y-valve and a second regulator, either one
of which can provide you with breathing gas from your tank. The regulator
complexity has just increased by a factor of 2, so the probability of a
regulator failure has doubled.  However, since simultaneous regulator
failures are required to bring the whole system down, the probability of a
system failure is MUCH less than the probability of a single regulator
failure (assuming the two regulators are truly independant entities, which
means they can be isolated in the event of a blown hose).*

*Note:  I've removed the math because it's incorrect....

Aloha,
Rich

Navigate by Author: [Previous] [Next] [Author Search Index]
Navigate by Subject: [Previous] [Next] [Subject Search Index]

[Send Reply] [Send Message with New Topic]

[Search Selection] [Mailing List Home] [Home]