Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261717AbVEPQBC (ORCPT ); Mon, 16 May 2005 12:01:02 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261720AbVEPQBC (ORCPT ); Mon, 16 May 2005 12:01:02 -0400 Received: from pop.gmx.de ([213.165.64.20]:58503 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S261717AbVEPQA5 (ORCPT ); Mon, 16 May 2005 12:00:57 -0400 X-Authenticated: #428038 Date: Mon, 16 May 2005 18:00:50 +0200 From: Matthias Andree To: "Richard B. Johnson" Cc: Jeff Garzik , Matthias Andree , linux-kernel@vger.kernel.org Subject: [OT] drive behavior on power-off (was: Disk write cache) Message-ID: <20050516160050.GE949@merlin.emma.line.org> Mail-Followup-To: "Richard B. Johnson" , Jeff Garzik , linux-kernel@vger.kernel.org References: <1115963481.1723.3.camel@alderaan.trey.hu> <20050515145241.GA5627@irc.pl> <200505151121.36243.gene.heskett@verizon.net> <20050516111859.GB13387@merlin.emma.line.org> <4288AF3A.2000008@pobox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-PGP-Key: http://home.pages.de/~mandree/keys/GPGKEY.asc User-Agent: Mutt/1.5.9i X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1036 Lines: 22 On Mon, 16 May 2005, Richard B. Johnson wrote: > Then I suggest you never use such a drive. Anything that does this, > will end up replacing a good track with garbage. Unless a disk drive > has a built-in power source such as super-capacitors or batteries, what > happens during a power-failure is that all electronics stops and > the discs start coasting. Eventually the heads will crash onto > the platter. Older discs had a magnetically released latch which would > send the heads to an inside landing zone. Nobody bothers anymore. IBM/Hitachi hard disk drives still use a "load/unload ramp" that entirely moves the heads off the platters - I've known this since the DJNA, and it is still advertised in Deskstar 7K500 and Ultrastar 15K147 to name just two examples. -- Matthias Andree - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/