From owner-freebsd-questions@FreeBSD.ORG Thu Aug 23 10:33:06 2007 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 3EB8E16A419 for ; Thu, 23 Aug 2007 10:33:06 +0000 (UTC) (envelope-from cjk32@cam.ac.uk) Received: from ppsw-5.csi.cam.ac.uk (ppsw-5.csi.cam.ac.uk [131.111.8.135]) by mx1.freebsd.org (Postfix) with ESMTP id CFFA213C459 for ; Thu, 23 Aug 2007 10:33:05 +0000 (UTC) (envelope-from cjk32@cam.ac.uk) X-Cam-SpamDetails: Not scanned X-Cam-AntiVirus: No virus found X-Cam-ScannerInfo: http://www.cam.ac.uk/cs/email/scanner/ Received: from gw.cjkey.org.uk ([88.97.163.222]:3969 helo=[192.168.2.186]) by ppsw-5.csi.cam.ac.uk (smtp.hermes.cam.ac.uk [131.111.8.155]:465) with esmtpsa (PLAIN:cjk32) (TLSv1:DHE-RSA-AES256-SHA:256) id 1IO9zr-0005eG-Hi (Exim 4.67) (return-path ); Thu, 23 Aug 2007 11:33:03 +0100 Message-ID: <46CD625E.7090508@cam.ac.uk> Date: Thu, 23 Aug 2007 11:33:02 +0100 From: Christopher Key User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Alex Zbyslaw References: <46CC1DB7.7040506@cam.ac.uk> <20070822152326.GF56142@gizmo.acns.msu.edu> <46CD58BB.9080001@dial.pipex.com> In-Reply-To: <46CD58BB.9080001@dial.pipex.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Jerry McAllister , freebsd-questions@freebsd.org Subject: Re: FreeBSD MBRs 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: Thu, 23 Aug 2007 10:33:06 -0000 Alex Zbyslaw wrote: > Jerry McAllister wrote: > >> You only need an MBR on disks that will be booted. I don't know as >> it will actually hurt anything to write an MBR on non-boot, data only >> disks, but it can garbage up you menu with non-functional choices. >> >> > What you need is an MBR on every disk which is *passed through* or > actually booted from. So if you have disks 1, 2 &3, if you want to > boot from disk3 you need an MBR on disks 1 & 2 as well, even if you > never boot from them. If you boot from disk 1, then 2 &3 do not > *need* an MBR. > >> Those other disk with an MBR show up as an F5 and maybe F6, etc ( >> > F5 is the *next* disk. There is no F6, F7 etc. > > If you boot from disk 3, for example, you'd go through three "menus" e.g. > > Disk1: F5 -> disk2 > Disk2: F5 -> disk3 > Disk3: F1 -> boots FreeBSD > > Thanks Jerry, Lowell and Alex, That clarifies a few points. Sorry the original post wasn't clear, I'll have a go at rexpressing my original questions using the above for context. Firstly, when you hit F5, does it, a) Load the partition table from the next disk and update the displayed list of slices, or b) Execute the MBR from the next disk? I'll assume the latter. Secondly, does boot0 'remember' that you pressed F5, and hence do the same the next time you boot, even after a power cycle? In this case, having done, Disk1: F5 -> disk2 Disk2: F5 -> disk3 Disk3: F1 -> boots FreeBSD the next time, it will appear as, Disk3: F1 -> boots FreeBSD The behaviour that I was experiencing was as follows: Disk1: F1 -> boots FresBSD reboot Disk1: F5 -> disk2 Disk2: Has /boot/mbr on it, and hence attempts to boot the active slice. As there is no active slice on the disk, simply fails with the message 'Missing operating system' Now, subsequent attempts to boot simply display the message 'Missing operating system'. Hence, I concluded that either, a) boot0 was rembering the F5 keystroke, and passing me on to disk 2 automatically, or b) That the BIOS was rememering something and booting straight from disk2 despite the boot order having disk1 first. The only was that I found to rectify this was use a boot from a USB device with boot0 on it: USB: F5 -> disk1 Disk1: F1 -> boots FreeBSD And now, subsequent reboots work fine: Disk1: F1 -> boots FresBSD I hope the above is a little more clear now. Regards, Chris