Re: BSD disklabel partition letters in NetBSD

[Michael van Elst <mlelstv%serpens.de@localhost>]

On Tue, Sep 25, 2018 at 05:05:44PM +0200, Rocky Hotas wrote:

> > only if none is written to disk,
> > a fictious label is generated from other data like an MBR.
> 
> Sorry, I can't understand this. Maybe it's related to the following
> description:

disklabel is a data structure. If there is none on the disk, it is
generated from other information.


> > The disklabel would be used and 'd' would still be the raw partition.
> > The disklabel would also be placed on sector 1.
> 
> So, two disklabels in total. But what would be the contents of the
> disklabel in sector 1?

With MBR, the disklabel is usually placed on relative sector 1 of
the MBR partition tagged as 'NetBSD' (type 169).

Without MBR, it is placed on absolute sector 1 of the medium.

N.B. the sector number can also be platform dependent, most use sector 1
but some use other sectors.


> > If you don't use disklabel but the wedge system, you get a device per
> > partitition, so there is no inherent limit.
> 
> I guess you are talking about GPT again.
> Sorry for having added some questions and thank you for all your information.

wedges are an abstraction that can be used for arbitrary partitioning
schemes, GPT is the most popular. But I use it for everything, including
disks that uses the BSD disklabel (you need a custom kernel for that).


Greetings,
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."