From owner-freebsd-hackers Mon Jul 8 20: 8:41 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D7D1337B400 for ; Mon, 8 Jul 2002 20:08:38 -0700 (PDT) Received: from postoffice.aims.com.au (eth0.lnk.aims.com.au [203.31.73.253]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1BBC143E31 for ; Mon, 8 Jul 2002 20:08:37 -0700 (PDT) (envelope-from chris@aims.com.au) Received: from postoffice.aims.com.au (nts-ts1.aims.private [192.168.10.2]) by postoffice.aims.com.au with ESMTP id g6938Zq80708 for ; Tue, 9 Jul 2002 13:08:35 +1000 (EST) (envelope-from chris@aims.com.au) Received: from ntsts1 by aims.com.au with SMTP (MDaemon.v3.5.3.R) for ; Tue, 09 Jul 2002 13:08:05 +1000 Reply-To: From: "Chris Knight" To: Cc: , Subject: RE: offtopic: low level format of IDE drive. Date: Tue, 9 Jul 2002 13:08:02 +1000 Message-ID: <004701c226f5$d7a0d540$020aa8c0@aims.private> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook CWS, Build 9.0.2416 (9.0.2911.0) In-Reply-To: <20020709024345.8095A3808@overcee.wemm.org> X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4807.1700 Importance: Normal X-Return-Path: chris@aims.com.au X-MDaemon-Deliver-To: hackers@FreeBSD.ORG Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Howdy, > -----Original Message----- > From: owner-freebsd-hackers@FreeBSD.ORG > [mailto:owner-freebsd-hackers@FreeBSD.ORG]On Behalf Of Peter Wemm > Sent: Tuesday, 9 July 2002 12:44 > To: chris@aims.com.au > Cc: silby@silby.com; hackers@FreeBSD.ORG > Subject: Re: offtopic: low level format of IDE drive. > > [snip] > > Does anyone have a detailed list of which SCSI drives do > > track writes rather than sector writes? > > You can find out by turning write caching on and off. > camcontrol modepage daN. You want -m 8, the WCE bit. (write cache > enable). I do not remember which -P args you need. > > If you see a HUGE difference in writing smallish blocks to disk > between WCE on vs off, then you have a track write drive. > > A true sectored drive would have much less of a slowdown. I do > not have a comparable set handy to get a better idea of what to > expect. > Really small writes cost scsi overhead though, so that adds to > the slowdown. If I was to take a best guiess, I would expect a > factor 10+ slowdown for track-write drives on 4K blocksize writes, > vs factor 2-5 slowdown for a sectored drive. > This is the slowdown factor when turning WCE off. > Excellent. This information should prove invaluable for future drive testing and acceptance. Thanks. > Cheers, > -Peter Regards, Chris Knight Systems Administrator AIMS Independent Computer Professionals Tel: +61 3 6334 6664 Fax: +61 3 6331 7032 Mob: +61 419 528 795 Web: http://www.aims.com.au To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message