From owner-freebsd-stable@FreeBSD.ORG Thu Dec 2 11:56:02 2004 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 01A9D16A4CE for ; Thu, 2 Dec 2004 11:56:02 +0000 (GMT) Received: from raven.ravenbrook.com (raven.ravenbrook.com [193.82.131.18]) by mx1.FreeBSD.org (Postfix) with ESMTP id D50A243D58 for ; Thu, 2 Dec 2004 11:56:00 +0000 (GMT) (envelope-from nb@ravenbrook.com) Received: from thrush.ravenbrook.com (thrush.ravenbrook.com [193.112.141.145]) iB2Btnuo079587; Thu, 2 Dec 2004 11:55:49 GMT (envelope-from nb@ravenbrook.com) Received: from thrush.ravenbrook.com (localhost [127.0.0.1]) iB2BtmrB047773; Thu, 2 Dec 2004 11:55:48 GMT (envelope-from nb@thrush.ravenbrook.com) From: Nick Barnes To: Ken Smith In-Reply-To: <20041202024052.GA11786@electra.cse.Buffalo.EDU> from Ken Smith of "Wed, 01 Dec 2004 21:40:53 -0500" Date: Thu, 02 Dec 2004 11:55:48 +0000 Message-ID: <47772.1101988548@thrush.ravenbrook.com> Sender: nb@ravenbrook.com cc: Joel Hatton cc: freebsd-stable@freebsd.org Subject: Re: 4.x can't read 5.x dump? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 02 Dec 2004 11:56:02 -0000 At 2004-12-02 02:40:53+0000, Ken Smith writes: > On Thu, Dec 02, 2004 at 10:48:43AM +1000, Joel Hatton wrote: > > > I'm backing up a 5.x machine at the moment with this command: > > > > dump -0Lau -b128 -f - /var | gzip -2 | ssh FreeBSD4 dd of=aacd0s1f.gz > > > > After the dump finishes, I try to read the file on the 4.x destination: > > > > # gzip -dc aacd0s1a.gz | restore -ivf - > > Verify tape and initialize maps > > Tape is not a dump tape > > > > I can scp the file back to the 5.x machine and it loads just fine, so what > > gives? This type of failure is somewhat scary for me right now, given that > > I may have to restore files to another destination that may not be 5.x > > based. > > This is, unfortunately, something that you should not expect to work > for any *nix variant. There's no theoretical reason why the formats used by dump and restore shouldn't be forward and backward compatible, allowing an older restore (to an older filesystem type) to pick out the parts of the dump which make sense to it while ignoring parts which it doesn't understand. But they aren't, so it can't, so you're out of luck. [In theory, the filesystem could package itself, so an old restore binary running on a newer filesystem and given a newer dump would DTRT]. Bikeshed, bikeshed. Nick B