From owner-freebsd-questions Fri Apr 21 11:44:11 2000 Delivered-To: freebsd-questions@freebsd.org Received: from merganser.its.uu.se (merganser.its.uu.se [130.238.6.236]) by hub.freebsd.org (Postfix) with ESMTP id 5A2E437B5C7 for ; Fri, 21 Apr 2000 11:44:08 -0700 (PDT) (envelope-from ertr1013@student.csd.uu.se) Received: from regulus.student.UU.SE ([130.238.5.2]:42125 "HELO ertr1013.student.csd.uu.se") by merganser.its.uu.se with SMTP id ; Fri, 21 Apr 2000 20:43:44 +0200 Received: (qmail 1133 invoked by uid 1001); 21 Apr 2000 18:43:31 -0000 Date: Fri, 21 Apr 2000 20:43:31 +0200 From: Erik Trulsson To: Artem Koutchine Cc: questions@FreeBSD.ORG Subject: Re: SCSI vs UDMA IDE 32-bit Message-ID: <20000421204331.A1115@student.csd.uu.se> References: <003601bfab80$82823c40$0c00a8c0@ipform.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0i In-Reply-To: <003601bfab80$82823c40$0c00a8c0@ipform.ru>; from matrix@chat.ru on Fri, Apr 21, 2000 at 02:58:15PM +0400 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Fri, Apr 21, 2000 at 02:58:15PM +0400, Artem Koutchine wrote: > I've made a little test. > I took a bunch of files (~130 MB) and copied them from > one filessystem to another. The HDD is IDE Quantum FB 10GB. > While copying i run top and saw about 80% of cpu wasted on > interupts. > > Then i anables 32bit access for the hdd and turned on DMA > transfers. Repeated the test and saw only tiny 0.8% wasted on > interupts, which is comparable to what SCSI takes. So, knowing > that SCSI and IDE hdd are based on the same mechanical parts why > should even use SCSI? Am I missing something? > The advantages of SCSI are really noticable noticable when you have several disks attached to the same controller. With modern disks and controllers SCSI and IDE are just as good if you only have a single disk attached. (And IDE disks are usually much cheaper.) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message