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Date: Thu, 11 Jul 1996 05:25:32 -0500
From: "Daniel M. Eischen" <deischen@iworks.InterWorks.org>
To: freebsd-questions@freebsd.org, mark@ucsalf.ac.uk
Subject: Re: Does Adaptec 7880 Ultra support simultaneous wide and narrow transfers?
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>   I have a motherboard with a built in 7880 Ultra with a narrow and a wide connector
> surface mounted. I have a Conner CFP4207S on the narrow channel with TERM/PWR enabled
> and a Conner CFP4207W on the wide channel with TERM/PWR enabled. I wanted to move my
> FreeBSD-2.1-stable filesystem from the narrow disk to the wide. I assumed that I could
> simply copy all the data over with (narrow on sd0, wide on sd1; with 512k on board
> data buffer):
>
> $ dd if=/dev/sd0c of=/dev/sd1c bs=512k
>
> However, this only yields data transfer rates in the 200K/s range. I've tried both
> larger and smaller buffer sizes with no apparent increase. I'm beginning to wonder
> if the 7870 chipset is performing these transfers simultaneously. I would expect
> such a command to push both drives at full speed with the drive access lights on
> solidly. However, the drive lights are alternating off/no for around 1 sec. periods.
> Am I expecting the wrong thing here?
> If I turn on WIDE negotiation for the W drive, the kernel enables 16bit transfers:

When did you get your -stable system?  There were some bug fixes that were incorporated
into the aic7xxx driver in late June.  Make sure you're running a -stable after that
date.

If you want to increase performance, add option "AHC_TAGENABLE" to your kernel
configuration.  If all your devices handle tagged queueing properly, then you
can try adding "AHC_SCBPAGING_ENABLE" to your kernel configuration also.

For devices on both internal narrow and wide channels, you should have termination
set to Low Off / High On.

Dan Eischen
deischen@iworks.InterWorks.org