Date: Tue, 29 Aug 1995 19:44:58 -0700 (PDT) From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> To: beckmann@powermac.stud.th-darmstadt.de (Michael Beckmann) Cc: vince@penzance.econ.yale.edu, freebsd-hardware@freebsd.org Subject: Re: Upgrade to my machine Message-ID: <199508300244.TAA05665@gndrsh.aac.dev.com> In-Reply-To: <v02130509ac694d4fda67@[130.83.177.6]> from "Michael Beckmann" at Aug 30, 95 01:10:08 am
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> > At 15:56 Uhr 18.8.1995, -Vince- wrote: > > > Hmmm okay but what drives can touch the barracuda's in terms of > >speed? > > The IBM DFHS line of drives, absolutely. 7 ms access, 7200 rpm, MTBF > 1.000.000 h. Available as both Fast - and Wide SCSI-II drives. I have nothing against IBM drives, but I do wish to point out a little known fact about MTBF numbers, they are reported as proper physics type of signifcant digit numbers, thus, 1,000,000 means somewhere between 500,000.0 and 1,500,000.0. IE, only the first digit in that number is signficant since it has no trailing decimal point. These are based upon calculations that where written many many years ago, and given light of technological changes once they go much above about 500,000 are pretty meaningless data until you can collect some reasonable large sample of FIT rates. Basically is what I am trying to say, is treat all things with MTBF numbers >500,000 hours as if they will last there technilogical life of 3 to 5 years and it does not really matter if it is 600K or 2M. > I would always prefer these drives and not buy a Barracuda, since I have > made very good experiences with IBM drives in both reliability and speed. I will agree with that, with one caveat, IBM also makes some of the most incompatible SCSI drives on the market. Drives that claim to be SCSI-II but can't do a device inquire is one example (0664). -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD
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