From owner-freebsd-stable Thu Sep 20 20:13:51 2001 Delivered-To: freebsd-stable@freebsd.org Received: from ece.cmu.edu (ECE.CMU.EDU [128.2.136.200]) by hub.freebsd.org (Postfix) with ESMTP id 7C46637B418 for ; Thu, 20 Sep 2001 20:13:47 -0700 (PDT) Received: from vpn58.ece.cmu.edu (1t6e63@VPN58.ECE.CMU.EDU [128.2.138.58]) (authenticated) by ece.cmu.edu (8.11.0/8.10.2) with ESMTP id f8L3D8P01935; Thu, 20 Sep 2001 23:13:09 -0400 (EDT) Date: Thu, 20 Sep 2001 23:13:04 -0400 From: "Brandon S. Allbery KF8NH" To: "David W. Chapman Jr." , "Daniel O'Connor" Cc: Nuno Teixeira , freebsd-stable@FreeBSD.ORG Subject: Re: hw.ata.wc && hw.ata.tags && softupdates short question Message-ID: <107060000.1001041983@vpn58.ece.cmu.edu> In-Reply-To: <20010920215107.B78811@leviathan.inethouston.net> References: <20010920211704.C7820@gateway.bogus> <20010920215107.B78811@leviathan.inethouston.net> X-Mailer: Mulberry/2.1.0 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline 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 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. -- brandon s. allbery [os/2][linux][solaris][freebsd] allbery@kf8nh.apk.net system administrator [JAPH][WAY too many hats] allbery@ece.cmu.edu electrical and computer engineering KF8NH carnegie mellon university [linux: proof of the million monkeys theory] To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message