From owner-freebsd-hackers@FreeBSD.ORG Sat Dec 18 21:18:54 2004 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id D67CA16A4CE for ; Sat, 18 Dec 2004 21:18:54 +0000 (GMT) Received: from srv1.cosmo-project.de (srv1.cosmo-project.de [213.83.6.106]) by mx1.FreeBSD.org (Postfix) with ESMTP id 1975543D3F for ; Sat, 18 Dec 2004 21:18:54 +0000 (GMT) (envelope-from ticso@cicely12.cicely.de) Received: from cicely5.cicely.de (cicely5.cicely.de [IPv6:3ffe:400:8d0:301:200:92ff:fe9b:20e7]) (authenticated bits=0) iBILIlSS063262 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=OK); Sat, 18 Dec 2004 22:18:49 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (cicely12.cicely.de [IPv6:3ffe:400:8d0:301::12]) by cicely5.cicely.de (8.12.10/8.12.10) with ESMTP id iBILHmrU033754 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sat, 18 Dec 2004 22:17:49 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (localhost [127.0.0.1]) by cicely12.cicely.de (8.12.11/8.12.11) with ESMTP id iBILHmet013149; Sat, 18 Dec 2004 22:17:48 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: (from ticso@localhost) by cicely12.cicely.de (8.12.11/8.12.11/Submit) id iBILHm9T013148; Sat, 18 Dec 2004 22:17:48 +0100 (CET) (envelope-from ticso) Date: Sat, 18 Dec 2004 22:17:47 +0100 From: Bernd Walter To: Peter Jeremy Message-ID: <20041218211747.GE1068@cicely12.cicely.de> References: <41C3D62D.7000808@comcast.net> <20041218091739.GC97121@cirb503493.alcatel.com.au> <20041218195910.GD1068@cicely12.cicely.de> <20041218210720.GE97121@cirb503493.alcatel.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041218210720.GE97121@cirb503493.alcatel.com.au> X-Operating-System: FreeBSD cicely12.cicely.de 5.2-CURRENT alpha User-Agent: Mutt/1.5.6i X-Spam-Status: No, hits=-4.9 required=3.0 tests=BAYES_00 autolearn=ham version=2.64 X-Spam-Report: * -4.9 BAYES_00 BODY: Bayesian spam probability is 0 to 1% * [score: 0.0000] X-Spam-Checker-Version: SpamAssassin 2.64 (2004-01-11) on cicely12.cicely.de cc: freebsd-hackers@freebsd.org cc: Gary Corcoran cc: ticso@cicely.de Subject: Re: Multiple hard disk failures - coincidence ? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: ticso@cicely.de List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 18 Dec 2004 21:18:54 -0000 On Sun, Dec 19, 2004 at 08:07:20AM +1100, Peter Jeremy wrote: > On Sat, 2004-Dec-18 20:59:11 +0100, Bernd Walter wrote: > >On Sat, Dec 18, 2004 at 08:17:39PM +1100, Peter Jeremy wrote: > >> My approach to this is to add a line similar to > >> dd if=/dev/ad0 of=/dev/null bs=32k > >> for each disk into /etc/daily.local (or /etc/weekly.local or whatever). > >> This ensures that the disks are readable on a regular basis. > > > >Regular reading of every file is part of what I call backup. > > That only verifies the used part of the disk. Reading the unused parts That's true - used parts are the only I'm interested in reading. If blocks fail that aren't used write reallocation has to do it's job. > of the disk as well helps reduce surprises. Also, in a mirrored environment, > the backup does not ensure that the data can be read off both disks. > (Or the parity area for RAID-5). Raid is another story. Just dd'ing the disks wouldn't check redundance integrity, but if you check the integrity why would you still want to check via dd too? -- B.Walter BWCT http://www.bwct.de bernd@bwct.de info@bwct.de