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Re: Promise or VIA?

On Mon, Sep 27, 2004 at 03:55:48PM +0200, Pep Turr? wrote:
> Hi,
> (this is a bit off-topic)
> On Wed, 22 Sep 2004 17:55:50 -0500, Pete Harlan <harlan@artselect.com> wrote:
> > The Asus A8V I bought has both a VIA and a Promise SATA controller,
> > and both work fine with Linux.  The Promise is better supported under
> > Linux (or possibly just a better controller; it does TCQ under Linux,
> > where the VIA doesn't (yet?)) as far as I could tell from the SATA
> > compatibility page.
> I was wondering: having both a Promise and a VIA SATA controllers and
> 2 hard drives: to implement software raid, which of these
> configurations would give better performance?:
> 1. One HD attached to a different controller (one to VIA, one to Promise)
> 2. Both HDs on the VIA controller
> 3. Both HDs on the Promise controller
> I guess that using a single controller would put more load on it but
> reduce the PCI bus load, and vice versa... am I right?

 Check your motherboard block diagram.  If the disk controller is attached
directly to the chipset, not through a 32bit/33MHz PCI bus, that's a Good
Thing.  If that's the case for only one of the controllers, you should
obviously use that controller.  (esp. don't use a controller that shares a
slow bus with gigE if you're going to do any file/web-serving.)

> >From the thread discussion, I would say that option 3 is better than 2
> (Promise being a better controller)... but is it better than option 1
> in overall performance on this scenario? what do you think?

 I agree.  Hard drives these days don't saturate 150MB/s SATA, except on
burst transfers to/from their cache.  W/ 2 drives, you might come close to
saturating 133MB/s 32bit 33MHz PCI.  faster/wider PCI busses,
hypertransport, or VIA's V-link (between north and southbridges) won't be a
bottleneck unless you have more drives.

#define X(x,y) x##y
Peter Cordes ;  e-mail: X(peter@cor , des.ca)

"The gods confound the man who first found out how to distinguish the hours!
 Confound him, too, who in this place set up a sundial, to cut and hack
 my day so wretchedly into small pieces!" -- Plautus, 200 BC

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