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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!simtel!pravda.aa.msen.com!spool.mu.edu!usenet.eel.ufl.edu!news.mathworks.com!tank.news.pipex.net!pipex!in1.uu.net!news.cloud9.net!cloud9.net!tls From: tls@cloud9.net (Thor Lancelot Simon) Newsgroups: comp.periphs.scsi,comp.os.linux.hardware,comp.os.linux.setup,comp.unix.bsd.freebsd.misc Subject: Re: SCSI diskIO Date: 23 Aug 1995 22:07:42 GMT Organization: Cloud 9 Internet, White Plains, New York, USA Lines: 42 Message-ID: <41g8re$11e@news.cloud9.net> References: <417ee7$1kp@trauma.rn.com> <419qu5$r4q@bonnie.tcd-dresden.de> <41fpji$g5a@overload.lbl.gov> <DDs7pM.KLA@ritz.mordor.com> NNTP-Posting-Host: cloud9.net Xref: euryale.cc.adfa.oz.au comp.periphs.scsi:36166 comp.os.linux.hardware:14120 comp.os.linux.setup:18030 comp.unix.bsd.freebsd.misc:5023 In article <DDs7pM.KLA@ritz.mordor.com>, Chris Mauritz <ritz@ritz.mordor.com> wrote: >Jin Guojun[ITG] (jin@gracie.lbl.gov) wrote: >: In article <419qu5$r4q@bonnie.tcd-dresden.de>, >: J Wunsch <joerg_wunsch@uriah.heep.sax.de> wrote: >: >news <news@trauma.rn.com> wrote: >: >>I can't decide on which controller to use. Is the 2940 my only option? >: >>I have access to an older 2940 (original one) however, I would like to >: >>know if there is a PCI SCSI host adapter for less money that runs faster >: >>than the 2940 under FreeBSD, Linux and DOS. >: > >: >Well, not faster, but almost at the same speed for very less bucks: >: >the NCR 52c810. I can easily suck 5 MB/s from a (not too fast) >: >Seagate disk over it, and 4.8 MB/s (each) when running two disks in >: >parallel. Ain't this enough for you? >: >-- >: >: I guess you mean 53c810 for 52c810. It is the most less expensive SCSI-2 >: controller and has the performance reach the SCSI-2 spec. >: I got 6.6 MBps reading rate on a sigle Seagate Baracuda disk and >: 8.5 MBps reading rate on double Seagate Baracuda disks on the same controller. >: It costs $55 now from ACME MICRO-SYSTEM Inc., and about $69 - $79 other places. >: > >So if these things are so fast and so cheap, why not use them instead >of something like the Buslogic 946C? There's not a whole lot of reason. The Buslogic will load the bus less because it takes its commands out of local memory on the board instead of by DMA from the host memory across the PCI bus. One could concievably build an 810 board with local RAM to supply commands but that would raise the price again. You also -- IMHO -- *don't* want to have to debug the NetBSD/FreeBSD NCR driver if it breaks. It makes extensive use of self-modifying code. In fact, both the code running on the host CPU and the code running on the NCR modify the code that runs on the NCR. This is unpleasant to contemplate. -- Thor Lancelot Simon tls@cloud9.net Don't let your mouth write no check that your tail can't cash. --Bo Diddley