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Newsgroups: comp.os.386bsd.questions Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!agate!howland.reston.ans.net!swrinde!ihnp4.ucsd.edu!ames!purdue!mozo.cc.purdue.edu!staff.cc.purdue.edu!bj From: bj@staff.cc.purdue.edu (Ben Jackson) Subject: How to get better SCSI performance? [FreeBSD 1.1R/AHA1542Cf] Sender: news@mozo.cc.purdue.edu (USENET News) Message-ID: <CrKBr2.8oJ@mozo.cc.purdue.edu> Date: Fri, 17 Jun 1994 22:28:14 GMT Organization: Purdue University Lines: 15 My system is a i486DX2/66 with 16M and (among other things) an Adaptec 1542Cf. There are three devices on the SCSI bus, a Maxtor LXT-213SY (SCSI1), a Quantum ProDrive 1800S (Fast SCSI2) and a NEC CDR500 (Fast SCSI2). Disconnection and Fast SCSI operation is enabled for all targets. The card it set for 8.0M/s DMA (although the TUNE_1542 option causes the driver to reprobe -- it gets the same value, 150nSEC). I'm getting pretty poor (IMHO) disk performance. Iozone output shows that by far most of my transfers are 650K/s (reading AND writing, which suggests that I'm losing out on my reading speed). Can anyone suggest experiments to improve my thoughput? Thanks, --Ben