nanog mailing list archives

Re: Limits of reliability or is 99.999999999% realistic


From: Shawn McMahon <smcmahon () eiv com>
Date: Mon, 27 Nov 2000 11:28:12 -0500

On Mon, Nov 27, 2000 at 11:07:34AM -0500, Marshall Eubanks wrote:

In spacecraft work, JPL has found that, if you did not
strive for "5 sigma's" or even "6 sigma's" of reliability, then
there would always be something you hadn't counted on that would
drive reliability to zero.

NASA's needs don't reflect our needs.

If my router fails, I can get to it to fix it in seconds, and if I need
to replace it I don't have to wait five years to launch and another year
to reach the target.

If I have to have a replacement overnighted, I'm still only down a day,
not a decade.

Also, NASA's budget for a POP on Mars is a little higher than my budget
for a POP in Colorado Springs.  Hell, their budget for a single lander
is probably higher than my budget for an entire data center.

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