Subject: Re: mounting partitions
To: None <netbsd-help@NetBSD.org>
From: James K. Lowden <jklowden@schemamania.org>
List: netbsd-help
Date: 03/07/2006 00:22:33
Vojko Kercan wrote:
> Below is my partition table (partition 0 is wher NetBSD 3.0 is
> installed):
> 
> 0: NetBSD (sysid 169)
>     start 63, size 188747622 (92162 MB, Cyls 0-11749), Active
> 1: NetBSD (sysid 169)
>     start 188747685, size 62926605 (30726 MB, Cyls 11749-15666)
> 2: NetBSD (sysid 169)
>     start 251674290, size 69998670 (34179 MB, Cyls 15666-20023/55/1)
> 3: <UNUSED>
...
> Judging by above outputs, to mount the remaining partitions (1 and 2) I
> should: mount /dev/wd0h and mount /dev/wd0i, yet mount produces an error
> "incorrect super block".

The problem with the term "partition" is its ambiguity.  Berlin was
partitioned for a long time.  Context is everything.  

http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q69912

Keep in mind that the MBR partition table first appeared in MS-DOS 2.0 to
cope with "big" hard disks i.e., drives larger than the largest filesystem
MS-DOS could create.  At the time, that meant 15 MB filesystems on 20MB
hard disks.  That would have been around 1984.  

Owing to its age and ubiquity on "IBM PC-compatible" hardware, lots of
operating systems, including NetBSD, have learned to interpret and respect
the MBR.  In so doing, they preserve other operating systems' data and
permit "dual-booting", etc. Like the Geneva Conventions, it mostly
controls what it's supposed to because not conforming is decidedly
unneighborly.   

The NetBSD kernel does not *use* the MBR partition table, though.  NetBSD
manages the disk via its disklabel.  Only this and nothing more.  

Obviously, if you have more than one OS using the disk, it's a good idea
if they both have one consistent view of it.  In such a case, you'd want
your disklabel partitions and your MBR partitions to share (some)
boundaries.  (Basically, all the disklabel partitions lie within the MBR
partition assigned to NetBSD.) But you're not trying to do that.  

Your MBR partition 0 covers the whole disk, which you intend solely for
NetBSD.  You should remove partitions 1.and 2 because they overlap sectors
with 0.  If anything ever tried to use them, they'd step on your NetBSD
system like a bulldozer on a putting green.  

Then set up your disklabel according to your needs.  You seem to know what
you want,so I won't advise you.  

HTH.  

--jkl