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	id sma009046; Sun Jan 26 12:44:35 1997
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Date: Sun, 26 Jan 1997 12:44:35 +0200
From: Nadav Eiron <nadav@barcode.co.il>
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To: "Eric J. Schwertfeger" <ejs@bfd.com>
CC: questions@freebsd.org
Subject: Re: SCSI Controller suggestions?
References: <Pine.BSF.3.95.970124171213.18358A-100000@harlie>
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Eric J. Schwertfeger wrote:
> 
   [snip]
> 
> I'm favoring the AHA2940 family, mostly because we already have two
> FreeBSD machines running them(Identified as <Adaptec 2940 SCSI host
> adapter> rev 0, not sure what that makes them), and I'd like to keep them
> all the same.
> 
> I've heard that unless bus saturation is important, the U and UW are
> actually slower than the base model, something to due with how many
> outstanding commands can be queued, if I remember correctly.  I'm
> currently favoring the AHA2940 for this reason.

You are probably referring to the difference between the A variants
(2940A, 2940AU) and the straight 2940. The 2940 can have 16 SCBs while
the A variants have only 3. I don't think it will make much of a
difference when you have just a single disk on the bus, but it has
nothing to do with the U or UW variants.

> 
> Also, the cpu this will be on is a P6/150 w/64M Ram.  Why?  Not because
> it needs it, but because at $520 for cpu and motherboard, it's cheaper
> than a P5/166 and motherboard).
> 
> Anyway, does anyone with more SCSI experience care to comment on the
> direction I'm going?
Nadav