From owner-freebsd-current@FreeBSD.ORG Mon Jan 19 14:26:27 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9364216A4CE for ; Mon, 19 Jan 2004 14:26:27 -0800 (PST) Received: from mta02-svc.ntlworld.com (mta02-svc.ntlworld.com [62.253.162.42]) by mx1.FreeBSD.org (Postfix) with ESMTP id 31D1143D5C for ; Mon, 19 Jan 2004 14:26:19 -0800 (PST) (envelope-from scott@fishballoon.org) Received: from llama.fishballoon.org ([81.104.195.124]) by mta02-svc.ntlworld.comESMTP <20040119222555.GFYB16066.mta02-svc.ntlworld.com@llama.fishballoon.org> for ; Mon, 19 Jan 2004 22:25:55 +0000 Received: from tuatara.fishballoon.org ([192.168.1.6]) by llama.fishballoon.org with esmtp (Exim 4.24; FreeBSD) id 1AihqM-000OKe-Pv for freebsd-current@FreeBSD.org; Mon, 19 Jan 2004 22:26:02 +0000 Received: (from scott@localhost) by tuatara.fishballoon.org (8.12.10/8.12.10/Submit) id i0JMQ1Ra000803 for freebsd-current@FreeBSD.org; Mon, 19 Jan 2004 22:26:01 GMT (envelope-from scott) Date: Mon, 19 Jan 2004 22:26:01 +0000 From: Scott Mitchell To: freebsd-current@FreeBSD.org Message-ID: <20040119222601.GB572@tuatara.fishballoon.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.1i X-Operating-System: FreeBSD 4.9-STABLE i386 Subject: vn vs. md - persistent swap-backed memory disk? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Jan 2004 22:26:27 -0000 Hi all, On 4.whatever, I can create a swap-backed vn(4) disk that will survive a reboot, following the recipe in the vnconfig manpage. All very useful for stuff in /tmp that I don't _really_ care about, but it's nice to have hang around anyway. The equivalent setup on a 5.2 box with md(4) doesn't behave in quite the same way: # mdconfig -a -t swap -o reserve -s 1g -u 1 # newfs -U /dev/md1 [...] # mount /dev/md1 /tmp # umount /tmp # mdconfig -d -u 1 # mdconfig -a -t swap -o reserve -s 1g -u 1 # mount /dev/md1 /tmp mount: /dev/md1 on /var/tmp: incorrect super block Same result if I don't use the 'reserve' flag, or if I bsdlabel md1 and mount md1c instead. I _can_ recover a filesystem on a file-backed md though. So just wondering if it's supposed to work this way, or if I'm doing something wrong setting it up? Scott -- =========================================================================== Scott Mitchell | PGP Key ID | "Eagles may soar, but weasels Cambridge, England | 0x54B171B9 | don't get sucked into jet engines" scott at fishballoon.org | 0xAA775B8B | -- Anon