[geeks] Fwd: [IP] Interesting speculation on the tech behind gmail

[Charles Shannon Hendrix]

Thu, 08 Apr 2004 @ 15:40 +0000, Lionel Peterson said:

> I don't follow your math... NOT saying you are wrong, but further insight
> appreciated.
> 
> If a drive has a MTBF of 100K hours, that comes out to what, about 400 24 hour
> days, right? Now, some drives may fail immediately (DOA+1 hour), other drives
> may last for 200K hours (giving a 100K hour mean), correct?

I think he meant to say 1,000,000 hours, and some drives are probably
over that now.

> Rather than a perfect linear failure rate (3 per day, for 400 days), the
> presumption is that the failures would tend to cluster around the 400 day
> mark, with very few failing in either the first 200 days or the last 200
> days... Right?

Maybe... of course, a lot depends on drive quality.  Regardless of
the MTBF, cheap drives have a pretty steady failure rate which
gradually gets worse.

Good drives don't behave the same way.

Of course, the bad drive manfucturer is probably fudging his MTBF
numbers.

> I would suspect that if the MB relies on a moving part (fan) it is likely to
> fail when the fan fails. If it does not rely on moving parts, it *could* run
> forever (seemingly)...

That's a good point.

Many fans out there are pretty crappy.  I suspect they'll fail at a very
high rate if they don't buy good ones from the start.


-- 
shannon "AT" widomaker.com -- ["I want this Perl software checked for
viruses.  Use Norton Antivirus." -- Charlie Kirkpatrick]