From owner-freebsd-hackers Wed Mar 10 11:31: 7 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from cc942873-a.ewndsr1.nj.home.com (cc942873-a.ewndsr1.nj.home.com [24.2.89.207]) by hub.freebsd.org (Postfix) with ESMTP id 39ADB14A2F for ; Wed, 10 Mar 1999 11:31:02 -0800 (PST) (envelope-from cjc@cc942873-a.ewndsr1.nj.home.com) Received: (from cjc@localhost) by cc942873-a.ewndsr1.nj.home.com (8.9.3/8.8.8) id OAA01900; Wed, 10 Mar 1999 14:30:31 -0500 (EST) (envelope-from cjc) From: "Crist J. Clark" Message-Id: <199903101930.OAA01900@cc942873-a.ewndsr1.nj.home.com> Subject: Re: using dd to make backup of disk? In-Reply-To: <199903101903.WAA25960@aaz.links.ru> from "Aleksandr A.Babaylov" at "Mar 10, 99 10:03:49 pm" To: babolo@links.ru (Aleksandr A.Babaylov) Date: Wed, 10 Mar 1999 14:30:31 -0500 (EST) Cc: cjclark@home.com, pete@bowtie.nl, hackers@FreeBSD.ORG Reply-To: cjclark@home.com X-Mailer: ELM [version 2.4ME+ PL40 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Aleksandr A.Babaylov wrote, > Crist J. Clark writes: > > Peter Weijmarshausen wrote, > > > Before you all start mailing me about how stupid it > > > is to use dd as a backup mechanism: I use this in > > > order to maintain an instant bootable backup. > > > So if the primary disk crashes I unplug it, reboot the > > > system and I have a working system again. > > > > Why is, > > > > # cd backupfs > > # dump -0af - origfs | restore -rf - > > > > Any less 'instant?' And 'dump' is meant to handle live filesystems. > dd is much faster. > boot codes and disk labels are not copied by dump|restore > only ufs (and ext2fs) can be copied by dump|restore That idea kind of scares me. You are assuming the two disks involved have identical geometries and characteristics when copying a disklabel. It just seems to me that dump|restore is a much safer alternative. Write the bootblocks and disklabel the backup manually once, then backup filesystems periodically. How often would the bootsectors and label change? -- Crist J. Clark cjclark@home.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message