From owner-freebsd-stable Sun Sep 23 3:45: 4 2001 Delivered-To: freebsd-stable@freebsd.org Received: from smtp8.xs4all.nl (smtp8.xs4all.nl [194.109.127.134]) by hub.freebsd.org (Postfix) with ESMTP id 7B28537B40D for ; Sun, 23 Sep 2001 03:44:59 -0700 (PDT) Received: from freebie.xs4all.nl (freebie.xs4all.nl [213.84.32.253]) by smtp8.xs4all.nl (8.9.3/8.9.3) with ESMTP id MAA13062; Sun, 23 Sep 2001 12:44:43 +0200 (CEST) Received: (from wkb@localhost) by freebie.xs4all.nl (8.11.6/8.11.4) id f8NAic009940; Sun, 23 Sep 2001 12:44:38 +0200 (CEST) (envelope-from wkb) Date: Sun, 23 Sep 2001 12:44:38 +0200 From: Wilko Bulte To: Matt Dillon Cc: "David W. Chapman Jr." , "Chad R. Larson" , "Daniel O'Connor" , j mckitrick , freebsd-stable@FreeBSD.ORG, Nuno Teixeira Subject: Re: hw.ata.wc && hw.ata.tags && softupdates short question Message-ID: <20010923124438.A9914@freebie.xs4all.nl> References: <20010921035414.B75668@dogma.freebsd-uk.eu.org> <20010922182052.B16388@freeway.dcfinc.com> <002501c143d0$78fa1b40$fe0c4042@inethouston.net> <200109230246.f8N2k2083827@earth.backplane.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: <200109230246.f8N2k2083827@earth.backplane.com>; from dillon@earth.backplane.com on Sat, Sep 22, 2001 at 07:46:02PM -0700 X-OS: FreeBSD 4.4-STABLE X-PGP: finger wilko@freebsd.org Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Sat, Sep 22, 2001 at 07:46:02PM -0700, Matt Dillon wrote: > > : > :As pointed out, its believed that IBM uses capacitors to fix this problem. > > I'm rather skeptical of this. If someone can point out the article > or technical spec then ok, but otherwise it's just rumor. It would take > a fairly large capacitor to hold the input voltages in spec long enough > to write out the cache. > > -Matt A larger cap, absolutely. In days long gone by disk manufacturers used the energy stored in the rotation of the platters to power an emergency head-retract on AC powerfail. Sometimes a small rechargable battery was used. Of course neither of this fits the requirements of a cache flush. The last thing you want to do is write on a disk that is not at nominal rpm. W/ -- | / o / /_ _ email: wilko@FreeBSD.org |/|/ / / /( (_) Bulte Arnhem, The Netherlands To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message