From owner-freebsd-scsi  Sat Sep 11  0:20:50 1999
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From: Don Lewis <Don.Lewis@tsc.tdk.com>
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Date: Sat, 11 Sep 1999 00:20:28 -0700
In-Reply-To: "Justin T. Gibbs" <gibbs@caspian.plutotech.com>
       "Re: data corruption when using aic7890" (Sep 10,  4:36pm)
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To: "Justin T. Gibbs" <gibbs@caspian.plutotech.com>,
	Andrew Gallatin <gallatin@cs.duke.edu>
Subject: Re: data corruption when using aic7890
Cc: "Justin T. Gibbs" <gibbs@plutotech.com>, scsi@FreeBSD.ORG,
	gibbs@FreeBSD.ORG, anderson@cs.duke.edu
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On Sep 10,  4:36pm, "Justin T. Gibbs" wrote:
} Subject: Re: data corruption when using aic7890
} >My tweak didn't seem to help either.  The default setting seem to 
} >be the most reliable.  Should I continue to tweak this variable, or do 
} >you have other ideas?
} 
} I would continue to tweak the variable.  I assume you tried setting
} the read threshold to MIN and the write threshold to MAX?  In other
} words, don't start a read from host memory until the FIFO is almost
} empty, and don't start a write to host memory until the FIFO is almost
} full.  The assumption here is that PCI is faster than the SCSI bus
} speed so we'll get the longest bursts this way.

Please tell me that this hardware doesn't silently corrupt data on a
FIFO underflow or overflow without at least setting a flag somewhere ...

I've got one of these at home and am getting ready to put three more
in service at work.


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