Date: Fri, 8 Oct 1999 10:11:46 -0700 (PDT) From: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> To: dg@root.com Cc: dwmalone@maths.tcd.ie (David Malone), dillon@apollo.backplane.com (Matthew Dillon), ady@warpnet.ro (Adrian Penisoara), freebsd-current@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG Subject: Re: [Patches avail?] Re: MMAP() in STABLE/CURRENT ... Message-ID: <199910081711.KAA49036@gndrsh.dnsmgr.net> In-Reply-To: <199910080934.CAA07195@implode.root.com> from David Greenman at "Oct 8, 1999 02:34:25 am"
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> >On Thu, Oct 07, 1999 at 10:09:23AM -0700, Matthew Dillon wrote: > > > >> Intel's ECC implementation is not perfect (1), but it's good enough to > >> catch these sorts of problems. > > > >Just as an interesting side note, we had a motherboard which > >supported ECC ram and had ECC ram in it and which was crashing. > >Eventually we discovered that every 8th byte in page aligned 4KB > >chunks was becomming corrupted. > > > >We replaced the ram and saw no improvement, and then got a replacement > >motherboard. As far as I could see the only significant difference > >between the new and old motherboard was the addition of a heat sink > >to the memory controler chip. The machine is now perfectly happy. > > > >So it seems that ECC isn't enough if your memory controler is too > >hot! > > ECC doesn't protect against certain types of motherboard address line > errors (since although the ECC is correct, the selected address is wrong, so > thus the data is wrong). There's parity protection on parts of the CPU > address bus, but I don't believe there is any protection between the memory > controller and the DIMMs for this type of problem. A handful of metal > filings is also known to cause problems when it is dispersed properly. :-) Your suppose to remove the motherboard before drilling holes in your chassis!!! :-). And be careful when you strip them there screws out, that little bit of metal filings is enough to through one for some real loops. A good blast of 60psi dry air does wonders for ``fixing'' some of these really strange problems :-) Now if I could just find something that would get sheet rock sanding dust out of tape drive mechanisms, a dunk in the freon tank often works, but that also cleans out all the lubrication :-). -- Rod Grimes - KD7CAX - (RWG25) rgrimes@gndrsh.dnsmgr.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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