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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!nntp.coast.net!news.kei.com!newsfeed.internetmci.com!howland.reston.ans.net!EU.net!peer-news.britain.eu.net!warwick!niss!bath.ac.uk!aber!io.salford.ac.uk!viking.ucsalf.ac.uk!not-for-mail From: mark@plato.ucsalf.ac.uk (Mark Powell) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Parity SIMMS really necessary? Date: 5 Dec 1995 17:36:48 -0000 Organization: Computer Services Unit, University College Salford, Salford, UK Lines: 35 Message-ID: <4a1vvg$fc0@plato.ucsalf.ac.uk> References: <49lbnr$4fq@interport.net> <49qabp$efi@zuul.nmti.com> <49spbi$1m8@sixpack.wustl.edu> NNTP-Posting-Host: plato.ucsalf.ac.uk In article <49spbi$1m8@sixpack.wustl.edu>, Matt Lundberg <ml@sixpack.wustl.edu> wrote: >In article <49qabp$efi@zuul.nmti.com>, Peter da Silva <peter@nmti.com> wrote: >>In article <49lbnr$4fq@interport.net>, >>David Tay <davidtay@interport.net> wrote: >>> I'm currently using FreeBSD with parity simms. There's a $50-$100 >>> difference with parity SIMMs. I would like to save some money and use >>> non-parity SIMMs. >> >>I'm obviously naive. I had no idea they even *made* non-parity SIMMs. >> >>The whole idea of putting that much memory in a box without at *least* >>parity (and preferably ECC) makes me sick in the stomach. > >As for using non-parity SIMMS, what does that extra bit give you >anyway? I agree that ECC is an advantage, but parity will only >inform you that you have a memory error, in most cases by locking >up the machine. This is no help. The idea is that when using parity SIMMS the system can detect a 1 bit error and lock-up the system without any resultant data loss. Without parity you will continue to think your data is fine when in fact it may be getting garbled. ECC SIMMS allow correction of 1 bit of errors and will lock-up the system when you get up to 2 bits of error (on the Apricot Shogun ECC system I've looked at.) It all depends on how much the possible corruption of your data will cost you. If it's less than the mentioned $50-$100 per SIMM then go ahead and use non-parity SIMMS. Otherwise you'd be wise to make the investment. >Matt Lundberg ml@sixpack.wustl.edu -- Mark Powell - Senior Network Technician - Room: C806 Computer Services Unit, University College Salford, Salford, UK. Tel: +44 161 745 3376 Fax: +44 161 736 3596 Email: mark@ucsalf.ac.uk finger mark@ucsalf.ac.uk (for PGP key) <A HREF="http://www.ucsalf.ac.uk/~mark/">Home Page</A>