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Date:      Thu, 11 Jan 2007 22:49:38 -0800
From:      Marcel Moolenaar <xcllnt@mac.com>
To:        Jo Rhett <jrhett@svcolo.com>
Cc:        stable@FreeBSD.org, Nikolay Pavlov <quetzal@zone3000.net>
Subject:   Re: 2.4TB disk - MBR and GPT coexist?
Message-ID:  <F3B0BD49-133C-4BD4-A747-68BD75F72D63@mac.com>
In-Reply-To: <D0D0CE06-B991-4945-B12B-152BA930106B@svcolo.com>
References:  <45A5FD8A.6080409@svcolo.com> <2918081F-D376-410B-B6FD-42BDD3323575@svcolo.com> <20070111213444.GB17185@zone3000.net> <D0D0CE06-B991-4945-B12B-152BA930106B@svcolo.com>

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On Jan 11, 2007, at 1:56 PM, Jo Rhett wrote:

> Since we're going to be stuck with old BIOSes for a long time after  
> 2TB is a cheap disk drive at [store], is anyone considering doing  
> the work to make GPT co-exist with an MBR block?

It is already possible for them to coexist. It's not uncommon in the
industry to use MBR partitions even though the disk has GPT. The
point is that you need to tools to avoid making a mess. Ideally you
want the MBR partitions mirrored by the GPT so that the kernel only
has to deal with GPT. The BIOS will use the MBR to boot.

The gpt(8) tool can actually be used to set this up. You partition
the disk with fdisk, but only for the boot partition. Then you run
gpt(8) to migrate the MBR into a GPT, specifying the -s option so
that you get a single GPT partition overlapping the MBR slice. After
that you restore the MBR partition. Now you can use GPT to define
a big partition. The kernel will use GPT and since you used -s when
you migrate the MBR, the kernel will create device nodes with the
same name as it would for the MBR partitions...

-- 
Marcel Moolenaar
xcllnt@mac.com





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