From owner-freebsd-questions@FreeBSD.ORG Fri Jul 15 21:41:48 2005 Return-Path: X-Original-To: freebsd-questions@FreeBSD.ORG Delivered-To: freebsd-questions@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id B12B316A41C for ; Fri, 15 Jul 2005 21:41:48 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id 52C1443D46 for ; Fri, 15 Jul 2005 21:41:48 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from localhost (localhost [127.0.0.1]) by pi.codefab.com (Postfix) with ESMTP id 8AE3E5E33; Fri, 15 Jul 2005 17:41:47 -0400 (EDT) Received: from pi.codefab.com ([127.0.0.1]) by localhost (pi.codefab.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 38113-08; Fri, 15 Jul 2005 17:41:38 -0400 (EDT) Received: from [192.168.1.3] (pool-68-161-54-113.ny325.east.verizon.net [68.161.54.113]) by pi.codefab.com (Postfix) with ESMTP id A04675C0F; Fri, 15 Jul 2005 17:41:37 -0400 (EDT) Message-ID: <42D82D96.9050900@mac.com> Date: Fri, 15 Jul 2005 17:41:42 -0400 From: Chuck Swiger Organization: The Courts of Chaos User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Stephen Hilton , freebsd Questions References: <38171.1121430073@thrush.ravenbrook.com> <42D7EBDE.8030807@mac.com> <42D80B5D.6060107@mac.com> <42D8200A.9060701@hiltonbsd.com> In-Reply-To: <42D8200A.9060701@hiltonbsd.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit X-Virus-Scanned: amavisd-new at codefab.com Cc: Subject: Re: better disk reliability on a desktop machine X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 Jul 2005 21:41:48 -0000 Stephen Hilton wrote: > Chuck Swiger wrote: [ ... ] >> Sure. But a single spare HD is a single point of failure. Having one >> tape per week or per month going back 10 or 100 tapes gives much more >> redundancy.... > > But were the tapes all generated by the same tape-drive? if so it is > once again a potential single point of failure. The created tapes > may not be readable by any other drive due to mis-alignment etc... > if that tape drive fails, the data on the tapes is lost also. It is true that tape alignment problems can make tapes unreadable, but the frequency of that sort of problem varies a lot by format: helical scan tapes such as DAT tend to have a lot more problems then linear formats like DLT or LTO/Ultrium. It is also a lot more likely that a data recovery company can make something out of a backup tape written by a misaligned drive than what you usually get from a blown hard drive. People design tapes, tape drives, and the on-media data format against the common sources of tape read errors, in part by using ECC prudently (again, the quality here can vary by format, and by the backup software being used). -- -Chuck