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Date: Sun, 7 Dec 2003 15:45:57 -0800 (PST)
From: Dan Strick <strick@covad.net>
Message-Id: <200312072345.hB7Njv1D000410@mist.nodomain>
To: current@freebsd.org
cc: kuriyama@imgsrc.co.jp
cc: dan@mist.nodomain
Subject: Re: SATA disks on 5.2-CURRENT
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On Mon, 08 Dec 2003 07:53:48 +0900, Jun Kuriyama wrote:
>
> Hmm, is there any performance loss by using legacy mode?
>

If you have two disk drives on a single SATA150 controller, they
can be accessed simultaneously in "native" mode because they are
on different ATA channels.  If the controller is operated in
"legacy" mode, the two disk drives appear to be on the same ATA
channel and only one can be used at a time though it may be
possible to do "overlapped" operations.

I have not attempted to measure a performance difference between
these two configurations.  The loss of an ATA channel is sufficient
reason to avoid legacy mode.

Dan Strick
strick@covad.net