Date: Wed, 30 Aug 1995 16:17:10 -0500 (CDT) From: Jim Bryant <jbryant@argus.iadfw.net> To: rgrimes@gndrsh.aac.dev.com (Rodney W. Grimes) Cc: freebsd-hackers@freebsd.org Subject: Re: S.O.S -2.1Stable and ASUSP54TP4 Message-ID: <199508302117.QAA04049@argus.iadfw.net> In-Reply-To: <199508300302.UAA05696@gndrsh.aac.dev.com> from "Rodney W. Grimes" at Aug 29, 95 08:02:01 pm
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In reply:
>
> Static memories are suspetable to alpha particule disturbance, it just
> takes a heck of a lot more to do it, and given ceramic is out of the
> picture it won't occur anyway. In a cmos static memory you have to have
> enough disturbance to perturb the gate voltage of one side of the latch
> to cause a bit flip, about 10 micro rinkens will do it, but it usually
> sends the device into latchup at the same time :-).
Also why static [Sandia process] memories are used in space and defense apps,
Gawd knows they have enough Alpha sources at Sandia to do it right...
> Current FIT per bit are in the 0.0002 to 0.0004 range, that is measure in
> billions of power on hours. Today MTBF in a 2MB x 16 bit DRAM subsystem
> is 30 to 35 years... I'd say I can live with that given that my disk
> is going to go belly up in 57 years anyway :-) :-) :-)
If you believe that, I have some beachfront property just west of Anacapa,
about 150 meters down... If that you believe that crap, then the 486-66 I
just replaced would be pushing 800 years old... Nobody except NASA, DoD,
and a few large companies probably have clean rooms environmentally and
power controlled enough to obtain these ridiculous MTBF ratings...
Shit, On my personal machine alone, in the last 8 months, I've been through
about 200 years worth of hard disks, hmmm, all seagate, I have yet to have
a modern hard drive from seagate last as long as 'ol betsy [my old st-4096
cover off, over fireplace]...
Jim
--
All opinions expressed are mine, if you | "I will not be pushed, stamped,
think otherwise, then go jump into turbid | briefed, debriefed, indexed, or
radioactive waters and yell WAHOO !!! | numbered!" - #1, "The Prisoner"
jbryant@argus.iadfw.net, Sr. System/Network Admin, Internet America
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