SunOS 4.x boot disk layout

[Jochen Kunz]

On Sun, 27 Mar 2005 12:12:27 +0000
Jules Richardson <julesrichardsonuk at yahoo.co.uk> wrote:

> Does anyone happen to know the organisation of a SunOS 4.x hard drive?
[...]
> However, obviously some space is taken up by the partition table
> itself, so the first (root) partition can't start at block zero. What
> I'm trying to find out is the offset that it does actually start at,
> so that I can mount the root partition from Linux. 
SunOS 4 is BSD and uses the BSD FFS. This in turn doesn't use the first
8 kB (16 blocks) in a slice. The first 8 kB (in slice a) are reserved
for the disklabel(5) and first stage boot code. Therefore slice a starts
at sector 0.

You may try to use NetBSD to mount those disks. In the days of NetBSD
1.4 I mounted a SunOS 4 drive from NetBSD/sparc without any trouble.
NetBSD uses the same disklabel(5) layout as Sun and the file system is
AFAIK just the same. (Nevertheless I recommend to mount read only or to
make a image backup before mounting read / write.) It should be easy to
boot your sun3 or sun4 machine diskless with NetBSD from a Linux box.

If you use a litle endian machine with NetBSD to analyze the disk read
options(4) about FFS_EI.
-- 


tschüß,
       Jochen

Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/