From owner-freebsd-stable Sat Sep 22 18:23:34 2001 Delivered-To: freebsd-stable@freebsd.org Received: from freeway.dcfinc.com (cx74889-a.phnx3.az.home.com [24.1.193.157]) by hub.freebsd.org (Postfix) with ESMTP id 4AD0837B428 for ; Sat, 22 Sep 2001 18:23:28 -0700 (PDT) Received: (from chad@localhost) by freeway.dcfinc.com (8.8.8/8.8.8) id SAA16494; Sat, 22 Sep 2001 18:20:52 -0700 (MST) (envelope-from chad) Date: Sat, 22 Sep 2001 18:20:52 -0700 From: "Chad R. Larson" To: "Daniel O'Connor" Cc: j mckitrick , freebsd-stable@FreeBSD.ORG, Nuno Teixeira , "David W. Chapman Jr." Subject: Re: hw.ata.wc && hw.ata.tags && softupdates short question Message-ID: <20010922182052.B16388@freeway.dcfinc.com> References: <20010921035414.B75668@dogma.freebsd-uk.eu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from doconnor@gsoft.com.au on Fri, Sep 21, 2001 at 12:26:07PM +0930 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 Fri, Sep 21, 2001 at 12:26:07PM +0930, Daniel O'Connor wrote: > On 21-Sep-2001 j mckitrick wrote: >>| Doesn't harware write cache usually write itself to disk before power >>| outage or even after? >> >> And wouldn't a laptop be safe with write caching? At least if I keep the >> battery in? > > Sure, but it is still a risk Years ago, there was a main-frame drive manufacturer who used the spindle motor as a generator in the case of a power failure. The kinetic energy in the spinning disk pack was converted to electricity, so there would be enough energy to flush the cache to disk and then park the heads. I think it was Century. You know, those drives that looked like small washing machines and had removable disk packs? I wonder if any of the current PC drive manufacturers do (or have considered doing) the same thing? -crl -- Chad R. Larson (CRL15) 602-953-1392 Brother, can you paradigm? chad@dcfinc.com chad@larsons.org larson1@home.com DCF, Inc. - 14623 North 49th Place, Scottsdale, Arizona 85254-2207 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message