Date: Wed, 6 Jan 1999 13:53:48 -0500 (EST) From: Ricky Beam <root@defiant.interpath.net> To: amlai@columbia.edu (Albert Max Lai) Cc: st0658@student-mail.jsu.edu, roe@spl-spindel.de, AIC7xxx@FreeBSD.ORG Subject: Re: SCSI speed with IBM DGVS09U (8 GB) hard drive, Linux Message-ID: <199901061853.NAA23329@defiant.interpath.net> In-Reply-To: <Pine.GSO.3.95qL.990103151050.8929A-100000@bonjour.cc.columbia.edu> from "Albert Max Lai" at Jan 3, 99 03:37:52 pm
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Letting the chips fall where they may, I quote Albert Max Lai: >On Sun, 3 Jan 1999, Andy Kennedy wrote: >> Jochen, >> I have a similar problem. From what I understand from information >> that has been given from people on the list, you cannot have one disc >> running at 40 and another running at 10???? I have 4 UW's and 1 N and I >> have to run all of the discs at 10. > >I thought that the ability to run discs at different speeds was a selling >point for Adaptec (or is that only on U2W adapers?). I have an aic-7895 >onboard a Tyan 1836DLUAN with a DGVS09U that runs at 40 MB/sec, a narrow >Quantum viking running at 20 MB/sec, and a Toshiba XM-3702TA CD-ROM >running at 4.4 MB/sec. So, at least for me, it seems that you can have a >variety of speeds on a single bus (all are connected to bus 0). U2 SCSI is LVD -- Low Voltage Differential. You generally cannot mix LVD and non-LVD devices on the same physical cable without causing problems. That does not say it cannot be done at all. As long as all the devices are SE (Singal Ended), then you can put the slowest crap SCSI-1 device on the bus with the most modern high speed SCSI-3 device. (That was part of the design spec from the beginning.) 20MHz and 40MHz are "Ultra" SCSI speeds (FAST-20 and FAST-40; UltraStor holds a TM/patent on "UltraSCSI") and your /proc output indicated ultra scsi was disabled. If in doubt, test the transfer speed with 'hdparm -Tt' --Ricky To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe aic7xxx" in the body of the message
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