From owner-freebsd-questions@FreeBSD.ORG Sun Jan 2 21:28:13 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 30A9B106564A for ; Sun, 2 Jan 2011 21:28:13 +0000 (UTC) (envelope-from jhs@berklix.com) Received: from tower.berklix.org (tower.berklix.org [83.236.223.114]) by mx1.freebsd.org (Postfix) with ESMTP id B1E408FC08 for ; Sun, 2 Jan 2011 21:28:12 +0000 (UTC) Received: from park.js.berklix.net (p5B22CB48.dip.t-dialin.net [91.34.203.72]) (authenticated bits=0) by tower.berklix.org (8.14.2/8.14.2) with ESMTP id p02LS956050780; Sun, 2 Jan 2011 21:28:10 GMT (envelope-from jhs@berklix.com) Received: from fire.js.berklix.net (fire.js.berklix.net [192.168.91.41]) by park.js.berklix.net (8.13.8/8.13.8) with ESMTP id p02LRwrY017965; Sun, 2 Jan 2011 22:27:58 +0100 (CET) (envelope-from jhs@berklix.com) Received: from fire.js.berklix.net (localhost [127.0.0.1]) by fire.js.berklix.net (8.14.3/8.14.3) with ESMTP id p02LRxSj037409; Sun, 2 Jan 2011 22:28:05 +0100 (CET) (envelope-from jhs@fire.js.berklix.net) Message-Id: <201101022128.p02LRxSj037409@fire.js.berklix.net> To: David Brodbeck From: "Julian H. Stacey" Organization: http://www.berklix.com BSD Unix Linux Consultancy, Munich Germany User-agent: EXMH on FreeBSD http://www.berklix.com/free/ X-URL: http://www.berklix.com In-reply-to: Your message "Sun, 02 Jan 2011 12:30:47 PST." Date: Sun, 02 Jan 2011 22:27:59 +0100 Sender: jhs@berklix.com Cc: freebsd general questions Subject: Re: Half a Mirror Backup 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: Sun, 02 Jan 2011 21:28:13 -0000 David Brodbeck wrote: > On Sun, Jan 2, 2011 at 11:56 AM, Jason C. Wells wrote: > > Is using one half of a mirror as a backup a good/bad idea? > > > > I was thinking of rotating drives on a periodic basis as a back up method. > >  You'd get the backup instantly, but rebuilding the mirror with the incoming > > drive would take a little time and leave you vulnerable to a small loss of > > data if a disk failed while the mirror was rebuilding. > > Besides the problem you mention, you'll have a pretty sizable > performance hit while the mirror is being rebuilt. Also, keep in mind > that the most likely time for a second drive to fail is during a > rebuild, since the rebuild forces a read from every sector. I think I > would use rsync or dump instead, although I have to admit the rotating > mirror idea is clever. Ref rsync: Personally I use rdist6, (from familiarity=habit rather than conscious choice, (it's more limited predecessor rdist, has been in BSD a Long time)) But beware: rdist6 fails on files bigger than 2G on i686 but (not on amd64, on amd64 no problem), I wouldnt know if rsync might have a similar 2G restriction. Cheers, Julian -- Julian Stacey, BSD Unix Linux C Sys Eng Consultants Munich http://berklix.com Mail plain text; Not quoted-printable, or HTML or base 64. Avoid top posting, it cripples itemised cumulative responses.