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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!nntp.coast.net!news.sprintlink.net!news-peer.sprintlink.net!news.mathworks.com!howland.erols.net!EU.net!main.Germany.EU.net!Dortmund.Germany.EU.net!interface-business.de!usenet From: j@ida.interface-business.de (J Wunsch) Newsgroups: comp.unix.bsd.freebsd.misc,comp.unix.bsd.bsdi.misc Subject: Re: Why one should buy parity memory for reliability? Date: 2 Oct 1996 11:57:12 GMT Organization: interface business GmbH, Dresden Lines: 29 Message-ID: <52tlao$9uf@innocence.interface-business.de> References: <32485B0D.41C6@austin.ibm.com> <52br3d$9s8@flash.noc.best.net> Reply-To: joerg_wunsch@interface-business.de (Joerg Wunsch) NNTP-Posting-Host: ida.interface-business.de X-Newsreader: knews 0.9.6 X-Phone: +49-351-31809-14 X-Fax: +49-351-3361187 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:28422 comp.unix.bsd.bsdi.misc:5046 dillon@best.com (Matthew Dillon) wrote: > Parity memory is important for several reasons: While i agree with this... > (1) memory densities are increasing and the smaller geometries are > susceptable to radiation. When you throw 512 MBytes onto a > machine, you need to *know* that it works. ...the ``radiation'' problem is something that has long since gone. At least, the original one. It was caused by alpha particles, since these are rather heavy-weighted (helium nuclei), thus they were able to discharge the memory capacitor at once all the time since the era of 64 kbit RAMs. However, due to their big size, these nuclei cannot penetrate even moderate amounts of harder material, even a few 10 µm's of plastics are a complete shield against them. Thus, any of our today's plastics IC cases is sufficient to shield even against a huge amount of them. The worst case were the old (and expensive) ceramics packages, they contained traces of beryllium which is a lightly nuclear-active material, and thus was generating the dangerous radiation itself. (The usual measure against this was to plastics- encapsulate the chip inside the case, or to put a PE foil above it before closing the case.) -- J"org Wunsch Unix support engineer joerg_wunsch@interface-business.de http://www.interface-business.de/~j