neese@adaptx1.UUCP (03/31/91)
>/* ---------- "SCSI slowness" ---------- */ > >I have a Quantum ProDrive 170S and an Adaptec 1522 controller (SCSI-2). >Supposedly, I should be getting upwards of 2 MB/sec out of this >combination, but when I use coretest (v 2.91), it tells me I am getting a >mere 900 k/sec. The ProDrive has a 64k cache built in on board. Some >system details: > Mylex MXA-33, 386 33 mhz motherboard > 8 mb ram > Adaptec 1522 SCSI-2 contoller > Quantum ProDrive 170S > DOS 4.01 > >I called adaptec but they weren't helpful. They said call your dealer, >since their dealers are supposedly knowledgeable about the card. Of course >this didn't work. I checked out all the manuals, and I think that I have >the zillion and one jumpers set correctly, but I am still sluggish. Any >clues??? Any ways I can check on the cache being implemented (it goes on >and off and changes sizes depending on the mode that the drive is running >in). The Quantum cache parameters are set in a pretty much generic manner. Not really tailored for any particular environment. If you reprogrammed the parameters to set the number of segments to 1 and the cache size for that segment to 128, you would get around 3MB/sec under coretest. You can verify the size Quantum has the cache set for by forciing coretest to use smaller block sizes. Around 16K or so you will see a performance increase. Probably around 2MB/sec or so. Of course, in the real world you probably won't get much of a performance gain, under DOS, unless you are really using a disk intensive program, but if you want coretest to show impressive numbers, you will need to reprogram the Quantum cache. Roy Neese Adaptec Senior SCSI Applications Engineer UUCP @ neese@adaptex uunet!cs.utexas.edu!utacfd!merch!adaptex!neese