On Wed, 25 Jan 2006, Julio M. Merino Vidal wrote:

> Hmm... just another fact which I discovered after sending the message.
> I first connected the 120gb drive as a slave of the older one (a 20gb
> disk that also does udma5). Then, I tried connecting it as a master
> of the second channel and it gives around 15 MB/s, which sounds much
> better to me. Why could this be?

Because the controller in the older drive is not as fast a controller,
and when it's the master, it's controlling the newer drive,
instead of the newer drive's controller. (Well, that's a bit of an
oversimplification, but it will do.)

For best performance, in general:

     1. Put drives on separate IDE controllers (separate cables) when
     possible.

     2. When two drives must share a controller (cable), the newer or
     faster drive should generally be the master.

When you're doing performance tests, use the raw device.

cjs
-- 
Curt Sampson            <cjs@cynic.net>             +81 90 7737 2974
   The power of accurate observation is commonly called cynicism
   by those who have not got it.    --George Bernard Shaw