DragonFly BSD
DragonFly kernel List (threaded) for 2004-03
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Re: Daemon's Advocate article

From: Chris Pressey <cpressey@xxxxxxxxxxxxxxx>
Date: Tue, 2 Mar 2004 00:54:40 -0800

On Tue, 2 Mar 2004 02:43:59 -0500
Rahul Siddharthan <rsidd@xxxxxxxxx> wrote:

> Chris Pressey said on Mar  1, 2004 at 23:39:10:
> > > > *BSD		The Rest of the World		DFly
> > > > ----		---------------------		----
> > > > slice		partition			partition
> > > > partition           N/A				subpartition
> > >                       ^^^
> > > I think the N/A should be "extended partition".  At least, my disk
> > > has four slices ("partitions" in rest-of-the-world speak), of
> > > which the
> > 
> > Yeah, thanks for catching that, my fingers outpaced my brain there.
> > I was thinking that I've not seen an equivalent in Windows (at least
> > not pre-NTFS....?)
> Extended partitions certainly existed back in MS-DOS days.  But
> I'm not clear how they relate to FreeBSD partitions except that when
> FreeBSD's on the last slice linux can mount its partitions as extended
> partitions.  (Windows, of course, knows nothing about ufs.)
> Rahul

OK, I'm a bit confused now.  (which is exactly what I'm hoping to avoid
in DFly's installer :)

I went and looked in Debian's install manual.  It says:
"``Primary'' partitions are the original partitioning scheme for PC
disks. However, there can only be four of them. To get past this
limitation, ``extended'' and ``logical'' partitions were invented. By
setting one of your primary partitions as an extended partition, you can
subdivide all the space allocated to that partition into logical
partitions. You can create up to 60 logical partitions per extended
partition; however, you can only have one extended partition per drive."

So, an extended partition looks like a special form of "primary"
(top-level) partition (BSD slice) which allows subdividing.  The
subdivisions themselves are called "logical partitions" (at least by
Debian.)  I don't know if that's the term DOS/Windows uses (or even if
they can use them, but I suppose they can, else why would they introduce
the idea of extended partitions.)

I had no idea you could only have one of these subdividable partitions
per disk, and certainly had no idea that it had to be the last partition
on the drive...


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