Date: Wed, 16 Aug 2006 14:51:57 +0200 From: Miroslav Lachman <000.fbsd@quip.cz> To: Danny Carroll <danny@dannysplace.net> Cc: freebsd-geom@FreeBSD.org Subject: Re: Mirror MBR? Message-ID: <44E314ED.3050305@quip.cz> In-Reply-To: <44E30387.5000203@dannysplace.net> References: <44E30387.5000203@dannysplace.net>
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Danny Carroll wrote: > Hello all. > > I had a question about gmirror. I am using Ralf S Engelschall's > mirroring solution at http://people.freebsd.org/~rse/mirror/ > > I used solution one, since I am sure that I will never be using any > different disks. It's a pizzabox server, and I don't expect data growth > so the current disks are fine. > > My main question is about the MBR. I dont see anywhere in the doc where > I should put a new boot record on the disk after doing: > > dd if=/dev/zero of=/dev/ad0 bs=512 count=79 > > Does this mean that the MBR from the mirror gets put onto this first disk? > > I ask because, I need to know what should happen when I need to replace > a disk. > > I know that after replacing the disk I should probably have to do > something like this: (Assume ad0 is the new disk) > > gmirror configure -a gm0 > gmirror insert gm0 /dev/ad1 > > But does that guarantee me that if ad0 fails, then I still have a > bootable system (assuming bios knows to boot of ad1). I am using gmirror from this HowTo: http://www.onlamp.com/pub/a/bsd/2005/11/10/FreeBSD_Basics.html After disk replacement (done today), I made just two commands: gmirror forget gm0 gmirror insert -v gm0 ad6 First command is to "forget about old (not available) disk drive", the second adds new disk in to mirror gm0 and start autosynchronization (configure -a is default, so is not needed) Gmirror can boot from any drive, I think MBR is on both drives. Miroslav Lachman
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