From owner-freebsd-stable Thu Sep 20 20:27:25 2001 Delivered-To: freebsd-stable@freebsd.org Received: from leviathan.inethouston.net (leviathan.inethouston.net [66.64.12.249]) by hub.freebsd.org (Postfix) with ESMTP id CBA7C37B417 for ; Thu, 20 Sep 2001 20:27:21 -0700 (PDT) Received: by leviathan.inethouston.net (Postfix, from userid 1001) id 8187510F4C1; Thu, 20 Sep 2001 22:27:27 -0500 (CDT) Date: Thu, 20 Sep 2001 22:27:27 -0500 From: "David W. Chapman Jr." To: "Brandon S. Allbery KF8NH" Cc: "David W. Chapman Jr." , Daniel O'Connor , Nuno Teixeira , freebsd-stable@FreeBSD.ORG Subject: Re: hw.ata.wc && hw.ata.tags && softupdates short question Message-ID: <20010920222727.E78811@leviathan.inethouston.net> Reply-To: "David W. Chapman Jr." Mail-Followup-To: "Brandon S. Allbery KF8NH" , "David W. Chapman Jr." , Daniel O'Connor , Nuno Teixeira , freebsd-stable@FreeBSD.ORG References: <20010920211704.C7820@gateway.bogus> <20010920215107.B78811@leviathan.inethouston.net> <107060000.1001041983@vpn58.ece.cmu.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <107060000.1001041983@vpn58.ece.cmu.edu> User-Agent: Mutt/1.3.22.1i X-Operating-System: FreeBSD 4.4-RC i386 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 Thu, Sep 20, 2001 at 11:13:04PM -0400, Brandon S. Allbery KF8NH wrote: > On Thursday, September 20, 2001 21:51:07 -0500, "David W. Chapman Jr." > wrote: > +----- > | > Well you can but if you lose power you WILL lose data. > | > > | Doesn't harware write cache usually write itself to disk before power > | outage or even after? > +--->8 > > My understanding is that modern drives typically have such large caches > that they can't actually guarantee flushing the entire cache to disk on > power failure before the capacitor(s) that store power for the purpose > discharge. You might be lucky if the cache is relatively empty, or you > might lose. > I'm just speculating, but on my drive with 2mb cache, that can sustain 20-30mb/sec writting, that's a tenth of a second. But my drive isn't the typical home user drive. -- David W. Chapman Jr. dwcjr@inethouston.net Raintree Network Services, Inc. dwcjr@freebsd.org FreeBSD Committer To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message