On Mon, Nov 25, 2002 at 06:41:16PM +0100, Mipam wrote:
> Hi,
> 
> The post of Richard Rauch stimulated me to post
> more on hd stuff with questions.
> I got two harddrives: a WD 2.5 gig and a WD 8.4 gig.
> I connected them on the primairy ide controller.
> Then i bought a 20 gig ibm drive.
> I planted the 2.5 WD drive on the secundairy controller
> together with the cdrom and the new ibm drive on the primairy
> controller together with the 8.4 wd drive.
> I noticed a significant downgrade of disk performance.
> Up till now i dont know, but it is very well possible
> that two disks of different brands dont go to well
> together on the same ide controller. Allthough ....

I've run into this already

> this shouldnt be the case and should be .... crap ... it could
> be possible. How else can i explain the downgrade of performance.
> Or perhaps my powersupply cant handle three disks and a cdrom
> properly?

I've also had power supply problems in the past.
Do the kernel show messages about IDE disks or controllers ?

> 
> Now i'm thinking on buying a promise tx2 ide controller
> which is a pci card, the netbsd pciide driver supports it now.
> Besides that ... im looking at a pci bus of 33 mhz and 32 bit.
> So theoretically .... 33*4 (bytes) is 132 mbyte/sec is the max
> speed of the pci bus ... so a udma 133 can never be fully supported
> and performance wise be reached by such a controller,
> unless you got a faster pci bus.
> And if i aint wrong the netbsd core wdc driver supports
> up to udma mode 5, so up to udma100.

No, UDMA 6 is supported now. But anyway I don't think the usual drives
can deliver data at that speed.


> So i still got to figure out if its really helpful to such
> a controller. Though ... im positive that it'll gain some performance
> at least. Anybody got some experience in this concerning performace
> and other stuff and/or bottlenecks?

Using an extra controller, and keeping only one device per channel is
a win, unless you never use these devices at the same time.

> In the case of such a controller i'll disable both the ide controllers on the
> mainboard in the bios.

I wouldn't do that, I would use the new controller to avoid master/slave

-- 
Manuel Bouyer <bouyer@antioche.eu.org>
     NetBSD: 23 ans d'experience feront toujours la difference
--