Re: BSD Disk labels
"Christopher C. Chimelis" <chris@debian.org> writes:
> On 14 Aug 2001, Falk Hueffner wrote:
>
> > the Debian installation manual says:
> >
> > "Another conventional requirement is for the `a' partition to start
> > from the beginning of the disk, so that it always includes the boot
> > block with the disk label."
> >
> > I'm not sure about this paragraph. If I start it from the very
> > beginning of the disk, I'd destroy the partition table when putting a
> > file system on it. Also, it'd conflict with aboot. Is this supposed to
> > be a dummy entry? If so, we should clarify it, and add a size
> > suggestion (say, 5mb).
>
> You're correct -- the installation manual is wrong for Alpha in this
> regard. I'm not sure about the size suggestion, though (I would actually
> go with a 2 sector pad, personally). Chances are, that sentence is a
> hold-over from the MILO-only times, btw, when the padding wasn't needed.
The section is from "Partitioning in Tru64 UNIX", so I assume it is
relevant for SRM users only. I've reformulated the section like this:
Partitions in the disk label may overlap. Moreover, the `c' partition
is required to span the entire disk (thus overlapping all other
non-empty partitions). Under Linux this makes sda3 identical to sda
(sdb3 to sdb, if present, and so on). Apart from satisfying this
requirement, you should carefully avoid creating overlapping
partitions.
Another conventional requirement is for the `a' partition to start
from the beginning of the disk, so that it always includes the boot
block with the disk label. If you intend to boot Debian from that
disk, you need to size it at least 2MB to fit aboot and perhaps a
kernel.
Note that these two partitions are only required for compatibility;
you must not put a file system onto them, or you'll destroy data. If
you're not going to share the disk with Tru64 Unix or one of the free
4.4BSD-Lite derived operating systems (FreeBSD, OpenBSD, or NetBSD),
you can ignore these requirements, and use the partitioning tool from
the Debian boot disks. See Debian Partitioning Programs, Section 6.5
for details.
Is that acceptable?
Falk
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