Date: Thu, 25 Feb 1999 16:59:41 -0500 (EST) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Darryl Okahata <darrylo@sr.hp.com> Cc: scsi@FreeBSD.ORG Subject: Re: dual-channel U2W scsi performance Message-ID: <14037.50689.119860.239392@grasshopper.cs.duke.edu> In-Reply-To: <199902252003.MAA06761@mina.sr.hp.com> References: <14035.5458.71518.652907@grasshopper.cs.duke.edu> <199902252003.MAA06761@mina.sr.hp.com>
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Darryl Okahata writes: > Andrew Gallatin <gallatin@cs.duke.ed> wrote: > > > Justin T. Gibbs writes: > > > > > > There must be something wrong with your cables. I've had several instance > > s > > > where a loose connector pin caused intermittent parity-errors. If both > > > the driver and the end device are reporting errors, they can't be wrong. > > > I've tested SE operation on the aic7896, so I know that it can work > > > with the current driver. > > > > Before I turned off parity in scsi-select, I tried all possible > > combinations of cabling (my setup is motherboard connecter -> internal > > cable -> external connector-> external cable -> box w/2 4G cheetahs -> > > active terminator), I switched out both cables, the external > > connector, the terminator & the box w/2 cheetahs.. No combination > > worked on the second channel. All combinations worked on the first > > channel. (by worked, I mean probed w/o parity errors) > > How long is the total cable length, starting at the motherboard? > At 20MHz, the max cable length is something like 1.5 meters, or a bit > less than 5 feet. Also, you are using high-quality external cables, > right? I'd estimate the total cable length at <= 1m. The cables are good quality, and the internal cable & external connector were actually temporarily borrowed from the secondary channel of a DPT raid setup (where the external connection is to an identical cable & identical box with 2 identical cheetahs). I trust the cables.. ------------------------------------------------------------------------------ Andrew Gallatin, Sr Systems Programmer http://www.cs.duke.edu/~gallatin Duke University Email: gallatin@cs.duke.edu Department of Computer Science Phone: (919) 660-6590 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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