From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263551AbTDTKiO (ORCPT ); Sun, 20 Apr 2003 06:38:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263552AbTDTKiN (ORCPT ); Sun, 20 Apr 2003 06:38:13 -0400 Received: from hermine.idb.hist.no ([158.38.50.15]:25869 "HELO hermine.idb.hist.no") by vger.kernel.org with SMTP id S263551AbTDTKiM (ORCPT ); Sun, 20 Apr 2003 06:38:12 -0400 Date: Sun, 20 Apr 2003 12:51:54 +0200 To: Valdis.Kletnieks@vt.edu Cc: linux-kernel@vger.kernel.org Subject: Re: Are linux-fs's drive-fault-tolerant by concept? Message-ID: <20030420105154.GA16451@hh.idb.hist.no> References: <20030419180421.0f59e75b.skraw@ithnet.com> <87lly6flrz.fsf@deneb.enyo.de> <20030419200712.3c48a791.skraw@ithnet.com> <20030419184120.GH669@gallifrey> <20030419205621.GA15577@hh.idb.hist.no> <200304192115.h3JLFVuL018983@turing-police.cc.vt.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200304192115.h3JLFVuL018983@turing-police.cc.vt.edu> User-Agent: Mutt/1.5.3i From: Helge Hafting Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Apr 19, 2003 at 05:15:31PM -0400, Valdis.Kletnieks@vt.edu wrote: > On Sat, 19 Apr 2003 22:56:21 +0200, Helge Hafting said: > > > There are commercially available programs that guarantees to > > wipe your drive clean - including hidden areas and remapped > > sectors. You should then be able to send drives > > back for warranty replacement. > > These don't address the problem - if the drive won't go "ready" because > of a blown server platter, your data won't get overwritten but it's still > readable (a number of companies make good money at this). > I see. Your data is so special that you expect people to pay for reconstruction hoping to find something that pays for all that trouble and more. > In general, if the disk is dead enough that you're looking at replacement, > you'll probably not be totally pleased with the results of those programs.. > I have replaced a couple of drives in my life - because a few sectors didn't read back right. I expect a overwrite program to be just fine under such circumstances. > > There are also bulk erasers that reset every bit magnetically, > > but those will probably void the warranty too. (You'll > > need a low-level reformat to recreate sector addresses on the > > suddenly blank surface.) > > Note that this only works well for single-platter disks - the field > you need to get the *inner* surfaces of the platters, especially for > a 5 or 6 platter disk, is quite astounding.... Why would it be hard to reach the inner surfaces - the disks are not superconducting so the outer ones do not shield the inner ones from a strong magnetic field. You should be fine as long as the field extend far enough to get the entire drive. A high-frequency device might have trouble, but you don't need that - even a static field will do. Helge Hafting