From owner-freebsd-hackers Mon Apr 1 09:59:27 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id JAA10907 for hackers-outgoing; Mon, 1 Apr 1996 09:59:27 -0800 (PST) Received: from ns.ge.com (ns.ge.com [192.35.39.24]) by freefall.freebsd.org (8.7.3/8.7.3) with ESMTP id JAA10792 for ; Mon, 1 Apr 1996 09:57:20 -0800 (PST) Received: from crissy.gemis.ge.com ([3.29.7.57]) by ns.ge.com (8.7.5/8.7.3) with SMTP id MAA06846; Mon, 1 Apr 1996 12:56:10 -0500 Received: from salem.ge.com (carsdb.salem.ge.com [3.29.7.15]) by crissy.gemis.ge.com (8.6.11/8.6.11) with SMTP id MAA19986; Mon, 1 Apr 1996 12:56:01 -0500 Received: from combs.salem.ge.com by salem.ge.com (4.1/SMI-4.1) id AA23976; Mon, 1 Apr 96 12:56:02 EST Received: from localhost (steve@localhost) by combs.salem.ge.com (8.7.5/8.6.11) with SMTP id MAA27897; Mon, 1 Apr 1996 12:56:01 -0500 (EST) Date: Mon, 1 Apr 1996 12:56:01 -0500 (EST) From: "Stephen F. Combs" Reply-To: CombsSF@salem.ge.com To: Luigi Rizzo Cc: davidg@Root.COM, dutchman@spase.nl, freebsd-hackers@freebsd.org Subject: Re: HDD cpu usage (IDE vs. SCSI). In-Reply-To: <199604011545.RAA23295@labinfo.iet.unipi.it> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Years ago we did a series of tests on PC's with IDE/EIDE/ST506/SCSI/etc.... Out of those tests came the following: If single-user O/S use single/multiple IDE(s) If multi-user O/S (WinNT, Unix, QNX, LynxO/S, etc.....) always, always use MULITPLE SCSI Disks w/SCSI Tape Backup. Wherever possible, on server systems, use multiple SCSI with Multiple SCSI controllers Single disk configurations IDE/SCSI were a wash in all configurations tested. The degradation in a multi-user O/S with multiple SCSI disks was less than 5%. With Multiple IDEs the degradation exceeded 50%. These were performed LOOOONG ago. ---- Stephen F. Combs Internet: CombsSF@Salem.GE.COM GE DS&TC Voice: 540.387.8828 Network Services Home: CombsSF-Home@Salem.GE.COM 1501 Roanoke Blvd FAX: 540.387.7106 Salem, VA 24153 LapTop: CombsSF-Mobile@Salem.GE.COM On Mon, 1 Apr 1996, Luigi Rizzo wrote: > Date: Mon, 1 Apr 1996 17:45:05 +0200 (MET DST) > From: Luigi Rizzo > To: davidg@Root.COM > Cc: dutchman@spase.nl, freebsd-hackers@freebsd.org > Subject: Re: HDD cpu usage (IDE vs. SCSI). > > > >How come the seagate uses twice as much cpu as the quantum? > > > > Because a Pentium-90 is much faster than a 486-100 for certain things and > > most of the %CPU is for total I/O overhead, not just the overhead in the > > device driver. > > Hmmm... if I get it right this means that under certain circumstances > (1 disk, onboard IDE controller, medium-fast CPU) using SCSI instead > of IDE gives you only a very little saving (which BTW is what I am > convinced of, but this has not been the dominating opinion on this > list). > > Luigi > ==================================================================== > Luigi Rizzo Dip. di Ingegneria dell'Informazione > email: luigi@iet.unipi.it Universita' di Pisa > tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy) > fax: +39-50-568522 http://www.iet.unipi.it/~luigi/ > ==================================================================== >