Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!apple!agate!shelby!rutgers!cbmvax!daveh From: daveh@cbmvax.commodore.com (Dave Haynie) Newsgroups: comp.sys.amiga Subject: Re: Amiga competitiveness Message-ID: <14910@cbmvax.commodore.com> Date: 5 Oct 90 16:50:05 GMT References: <2070@lpami.wimsey.bc.ca> Reply-To: daveh@cbmvax.commodore.com (Dave Haynie) Organization: Commodore, West Chester, PA Lines: 45 In article <2070@lpami.wimsey.bc.ca> lphillips@lpami.wimsey.bc.ca (Larry Phillips) writes: >In <14821@cbmvax.commodore.com>, daveh@cbmvax.commodore.com (Dave Haynie) writes: >>ST-506 and EDSI have problems of interleave setup, not usually a problem with >>SCSI, that result in factor of 10 or more preformance changes. >Gee... I'm running an ESDI drive. Of course I have it hanging off a >SCSI<->ESDI adapter. It's pretty fast.. a LOT faster than any ST506 I have run >either off the 2090 or off a SCSI<->ST506 adapter (may have been partially >due to the adapter being a cheapo Adaptec 4000). The ESDI drive gets about >700KBytes/sec on the 3000, using an Emulex MD-21 controller. Let me clarify -- I didn't mean that the SCSI should be 10x the speed of the EDSI, but that, based on the controller specifics, the interleave you use on the EDSI (or ST-506) drive can vary that drive's preformance by a factor of 10 or so, just sticking to common values. While interleave of of course a fact of life with any hard drive, the vast majority of SCSI drives are preset to the optimal value, since the low level driver and physical drive are both perfectly under the control of the SCSI drive vendor. So it's very possible to set a bogus interleave value when adding an ST-506 or EDSI drive to a system, but almost impossible to screw up a SCSI drive's interleave. >> It's impossible to know just what you have working against you. Could be the >> disk interleave. Could be it's not really formatted FFS. Could be ... >Boy are you right on with that! The smallest things, set up poorly, can make >the difference between a 200KBytes/sec and an 800KBytes/sec transfer rate. >Happens all the time, and we see a lot of griping about slow disks because of >it. Well, that's life in the fast lane. If we didn't make it so fast in the first place, it wouldn't be quite so sensitive to little changes :-) >It is not possible to both understand and appreciate Intel CPUs. > -D.Wolfskill >| // Larry Phillips | -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Standing on the shoulders of giants leaves me cold -REM