Date: Mon, 8 Feb 1999 13:53:50 -0500 From: "Smith, Jeremy" <SmithJ@mps.bellhowell.com> To: "'Beau James'" <bjames@cisco.com>, aic7xxx@FreeBSD.ORG Subject: RE: SCSI bus topology questions Message-ID: <61F2369A784ED211B22D00104B59E210800B@bhtriex.mps.bellhowell.com>
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If I'm not mistaken the disable/enable option is for the low-byte SE terminator on the SCSI bus. This is the only term shared between any of the "plugs". High-Byte UW should always be termed in this setup and High/Low-byte U2W should always be termed. If both of the SE connectors are in use then the Low byte on the bus would not need to be terminated by the host adapter as it is in the middle of the bus. The Low byte should be terminated with good quality terminators on either end of the SE bus. Often times the terms on CD-ROMS, tape drive and the like are not of very good quality. Try disabling the terminator in the SCSI Bios and if that fails get a couple of active terminators to put on the ends of your cables. Hope this helps. ----------------------------------------------------------- Jeremy Smith System Administrator Bell+Howell MPS smithj@mps.bellhowell.com 1400856@mcipage.com Day: (919)767-6530 Eve: (919)859-5690 ------------------------------------------------------------ -----Original Message----- From: Beau James [mailto:bjames@cisco.com] Sent: Monday, February 08, 1999 1:39 PM To: aic7xxx@FreeBSD.ORG Subject: SCSI bus topology questions This is not strictly an AIC7xxx question, but an AIC3640 question regarding the ASUS P2B-S or similar motherboards. I haven't been able to sort this out from the documentation. There are three SCSI connectors on the motherboard: 68-pin (U2W LVD) 68-pin (UW SE) 50-pin (UW SE) The U2W LVD segment is always terminated on the motherboard, and must be terminated at the far end of the LVD device chain, according to the ASUS documentation. Questions: - Is the motherboard host adapter in the center of the 50-pin and 68-pin bus segments? - Does the "Disable termination" setting in the Adaptec BIOS refer to the host adapter (motherboard) SE bus termination? That is, if I need to attach devices to both the 50-pin and 68-pin SE segments, should I turn off the termination in the Adaptec BIOS? What prompts the question is that when I add a disk on the 68-pin SW segment, the disk is identified correctly during the Adaptec BIOS SCSI bus probe. But the system then fails to boot - it hangs in the BIOS. Which is making it tough to install Linux on the new disk. Thanks for any tips. Beau +-------------------------+---------------------+--------------------------- + + || || + Cisco Systems, Inc. + Beau James + + || || + 170 West Tasman Dr. + Mgr, xDSL Switch S/W + + |||| |||| + San Jose, CA 95134+ Phone: (408) 526-8328 + + ..:||||||:..:||||||:.. + + FAX: (408) 527-0495 + + Cisco Systems Inc. + + Email: bjames@cisco.com + +-------------------------+---------------------+--------------------------- + To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe aic7xxx" in the body of the message To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe aic7xxx" in the body of the message
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