From owner-freebsd-hackers  Sat Oct 25 14:51:57 1997
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Date: Sat, 25 Oct 1997 21:51:44 +0000
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To: Tom <tom@sdf.com>
CC: freebsd-hackers@FreeBSD.ORG
Subject: Re: Parity Ram
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Tom wrote:
> 
> On Sat, 25 Oct 1997, Jamil J. Weatherbee wrote:
> 
> > Can someone fill me in on when you would want to use parity ram as opposed
> 
>   Why?  To discover memory problems before they corrupt data, and cause
> random panics, core dumps, hangs, or file system corruption.  Personally,
> I use ECC capable motherboards that can actually use parity to fix some
> errors.

You need EDO ram I think for this to work, You need some memory to keep 
information of what is in your memory before.
 
> > to non-parity ram these days?  If there was some anomaly in memory how
> > would freebsd handle it (is there a trap for parity error?)
> 
>   These days?  RAM can fail.  Nothing has changed in the last 10 years.
> I've bought about a gig of RAM in the last couple of months, a good
> percentage of SIMMs still arrive DOA.
> 
>   FreeBSD systems simple reboot upon parity errors.  This is pretty safe
> thing to do.  Much better than what a non-parity system would at this
> point (ex. corrupt your filesystems).  A smarter thing to do, might be to
> simple stop the process owning the memory that failed, and flag the area
> as unusable (NT does this).  Doesn't help much if kernel is in the bad
> memory area though.
> 
> Tom