Subject: Re: Recursive partitioning
To: Hubert Feyrer <hubert@feyrer.de>
From: Bill Stouder-Studenmund <wrstuden@netbsd.org>
List: tech-kern
Date: 06/05/2007 21:31:59
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On Wed, Jun 06, 2007 at 12:31:42AM +0200, Hubert Feyrer wrote:
> On Tue, 5 Jun 2007, Martin Husemann wrote:
> >Fixing remaining issues (like bootloader support) instead and going
> >with gpt and wedges sounds a lot easier to me - and I'm not sure what
> >recursive partitioning would add, feature wise.
>=20
> Pardon my ignorance, but: do we really want to bother with GPT, now that=
=20
> even Apple can boot from systems with an MBR?

Yes.

MBR, Apple partitoin maps, and disklabel labels all use 32-bit nubmers to=
=20
count sectors. Thus they have issues with disks larger than 2 TiB (2^32=20
blocks). You can play games with block sizes, but that will get you only=20
so far. And it will be very non-portable.

As far as I can tell, Windows and Mac OS have standardized on GPT for such=
=20
disks, and I think Linux also uses only GPT for them. Thus GPT is the=20
choice for such disks.

So we need GPT regardless of what else we may do.

Given that we need GPT, it makes sense to use it as a way to clean up a
number of other issues. GPT, especially with wedges, is not limited to a=20
fixed number of partitions. It's been designed to not have a number of=20
issues we've faced with our current labeling options.

GPT maps also have the advantage that all OSs can understand the=20
partitions. Yes, not much other than NetBSD will understand our file=20
system, but Windows and Mac OS and Linux will know where our partitions=20
start and end. So if you end up needing to reclaim a partition while=20
running another OS, you can.

Take care,

Bill

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