Date: Fri, 14 Apr 1995 13:59:42 -0700 (PDT) From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> To: jaitken@cslab.cs.vt.edu (Jeff Aitken) Cc: nate@trout.sri.MT.net, freebsd-scsi@FreeBSD.org Subject: Re: SCSI target Message-ID: <199504142059.NAA01671@gndrsh.aac.dev.com> In-Reply-To: <199504142054.QAA31915@husky.cs.vt.edu> from "Jeff Aitken" at Apr 14, 95 04:54:52 pm
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> > > > > > Your not going to get much more out of *any* ISA controller. The 1542CF > > > will do a little better, but basically your problem is the speed of > > > the ISA bus bus mastering (typical max is 5MB/sec *burst*, sustainted > > > goes down to about 3.7-4MB/sec). You should be getting about 3MB/sec > > > out of your 1542B and I have not seen anthing better on ISA. > > > > I *should* be seeing 3MB/sec, but I've never got #'s even close. > > > > This is with 2.0R install created FS's. > > > > Writing the 32 Megabyte file, 'iozone.tmp'...31.257812 seconds > > Reading the file...24.953125 seconds > > > > IOZONE performance measurements: > > 1073473 bytes/second for writing the file > > 1344698 bytes/second for reading the file > > > Maybe I'm just not understanding something here, but shouldn't I be > getting better than 3MB/s with both the NCR Fast-SCSI2 controller + a > Micropolis Fast-SCSI2 drive? (486DX2/66, 16MB, PCI/ISA, 256K cache) Depends on the model of the drive, I need to know how fast it spends and how many heads and cylinders there are. If you have the sectors/zone info that helps too. Basically max sustained transfer rate is: MB/sec == (#sectors per track) * (RPM / 60) * 512 For Zone Bit Recorded drives (any modern scsi drive is ZBR) you will get higher transfer rates on the lower numbered cylinders. > % iozone 32 Can't say much with the model drive it was on, and the parameters of said drive. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Custom computers for FreeBSD
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