From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([69.77.167.62] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1JVjvG-0004sC-0b for garchives@archives.gentoo.org; Sun, 02 Mar 2008 08:51:54 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 996A5E060D; Sun, 2 Mar 2008 08:51:52 +0000 (UTC) Received: from smtp4.clear.net.nz (smtp4.clear.net.nz [203.97.37.64]) by pigeon.gentoo.org (Postfix) with ESMTP id 509A6E060D for ; Sun, 2 Mar 2008 08:51:52 +0000 (UTC) Received: from zmori.markir.net (121-72-69-134.dsl.telstraclear.net [121.72.69.134]) by smtp4.clear.net.nz (CLEAR Net Mail) with ESMTP id <0JX3001V2HYDFK30@smtp4.clear.net.nz> for gentoo-user@lists.gentoo.org; Sun, 02 Mar 2008 21:51:50 +1300 (NZDT) Date: Sun, 02 Mar 2008 21:51:47 +1300 From: Mark Kirkwood Subject: Re: [gentoo-user] Ghosting a Ext3 partition In-reply-to: <20080302074815.GK9879@avlebavle.dk> To: gentoo-user@lists.gentoo.org Message-id: <47CA6AA3.4080404@paradise.net.nz> Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: <200802291227.35724.Jonathan.Haws@sdl.usu.edu> <959274.49799.qm@web31707.mail.mud.yahoo.com> <20080301203641.5246b692@pascal.spore.ath.cx> <47CA2D41.6030003@paradise.net.nz> <47CA323A.1080403@paradise.net.nz> <20080302074815.GK9879@avlebavle.dk> User-Agent: Thunderbird 2.0.0.9 (X11/20071203) X-Archives-Salt: c02fdfc7-67d8-43b8-b2bc-47a6c6986438 X-Archives-Hash: 0a1dd1298c4100a1f0abd6510fad25e4 Rasmus Andersen wrote: > > If you do backup live filesystems/data then dump is on par with dd; both > read from the underlying device and might bypass the kernel's page cache. > Ie., there might be unwritten data cached thats not on disk yet. > Tar/rdiff-backup/etc reads through the pagecache and avoids this problem. > > The dump people talk a bit about this themselves on > > http://dump.sourceforge.net/isdumpdeprecated.html > > Note I dont want to dis dump, backing up live filesystems is just tricky > (depending on your consistency requirements :) and dump adds another > level to that. > > > Understood - I have seen that article too. I must say, I've mainly had experience with 'dump' on Freebsd and 'xfsdump' on Linux, and never had restore issues with *either* of these. Now I'm not sure whether these are supposed to be better than 'dump' on Linux aimed at ext2|3 filesystems - certainly Freebsd's 'dump' has an option to tell it that it is dumping a 'live' filesystem, and the man pages for xfsrestore have notes concerning what happens when restoring an (xfs)dump from a 'live' filesystem - so they may well be! On the other hand I've certainly routinely seen cases of people using dd (rsync, cpio, tar etc) and coming to grief at restore time. I am reluctant to suggest that folks use xfs and hence get access to xfsdump, as one of the nice things about Linux is the choice of a variety of filesystems - but it is pretty important to get able to backup of (for instance ) / ... and you usually don't have much option other than doing it live! regards Mark -- gentoo-user@lists.gentoo.org mailing list