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Date:      Thu, 24 Feb 2000 16:47:04 +0100
From:      Brad Knowles <blk@skynet.be>
To:        freebsd-stable@FreeBSD.ORG
Subject:   Re: Multiple Adaptec 2940U2W controllers?
Message-ID:  <v0422080db4db01ea81fc@[195.238.1.121]>
In-Reply-To: <v0422080cb4daf715f6bf@[195.238.1.121]>
References:  <v0422081fb4d9d7f862b6@[195.238.1.121]> <v04220834b4da0a913e9e@[195.238.1.121]> <v0422080cb4daf715f6bf@[195.238.1.121]>

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At 4:04 PM +0100 2000/2/24, Brad Knowles wrote:

>  	Now that the problem has been fixed, initial preliminary test
>  results indicate that I do actually see almost 2x speedup using
>  two host SCSI controllers to the two different drive array
>  controllers. I'm now moving one of the host SCSI adaptors back
>  to the other PCI bus, to see if that helps, hurts, or makes no
>  difference to the performance.
>
>  	If it doesn't hurt, I plan on leaving them on separate PCI busses.

	Blargh.  It does appear to hurt.  I'm trying the two 2940U2W 
controllers on the primary PCI bus with the on-board AIC-7890 
controller hard-wired to the secondary PCI bus.  If that doesn't work 
(and I don't suspect it will, but I want to test it for the sake of 
completeness), then for this machine the only solution appears to be 
to put SCSI controllers on the secondary PCI bus and everything else 
on the primary PCI bus.

	If that's the case, I'm going to be quite annoyed.  That will 
mean that I cannot expand the number of SCSI busses in this machine 
by just adding more controllers.  Instead, I will be forced to 
increase the number of SCSI channels by swapping out the current 
controllers and using 3950U2W controllers instead.


	Blargh.  Double blargh.  Blargh, say I.



	BTW, is anybody at all actually interested in this stuff, or am I 
just talking to myself?

-- 
   These are my opinions and should not be taken as official Skynet policy
  _________________________________________________________________________
|o| Brad Knowles, <blk@skynet.be>                 Belgacom Skynet NV/SA |o|
|o| Systems Architect, Mail/News/FTP/Proxy Admin  Rue Col. Bourg, 124   |o|
|o| Phone/Fax: +32-2-706.13.11/726.93.11          B-1140 Brussels       |o|
|o| http://www.skynet.be                          Belgium               |o|
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     Unix is like a wigwam -- no Gates, no Windows, and an Apache inside.
      Unix is very user-friendly.  It's just picky who its friends are.


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