Sparc64 partitions compatible with PC?

[Miles Nordin]

>>>>> "dm" == Didrik Madheden <didrik at kth.se> writes:

    dm> I have a Sparc box that I use mainly as an FTP
    dm> server. (SunBlad 100 if it makes a ny difference) What I want
    dm> to do now is to move that disk to an x86 box.

backup the disk label to a text file on the sparc box, and move it to
the PeeCee OOB.  

then load the label onto the disk on the peecee.  this writes to the
disk, and may make it unreadable on both machines because it might go
wrong, or general compatibility prudery and kludges on the peecee may
eat up a larger fixed portion at the beginning of the disk making it
impossible to line up the start of your first filesystem properly.

It is possible to put plain BSD labels onto FreeBSD/i386 disks:

pizarro:~$ uname -a
FreeBSD pizarro 6.0-RELEASE FreeBSD 6.0-RELEASE #1: Tue Nov  8 20:23:54 UTC 2005     carton at cortez:/usr/src/sys/i386/compile/CORTEZ  i386
pizarro:~$ df -k
Filesystem 1K-blocks    Used   Avail Capacity  Mounted on
/dev/ad4a      63214   34552   23606    59%    /
devfs              1       1       0   100%    /dev
/dev/ad4e    7615086 2864168 4141712    41%    /usr
devfs              1       1       0   100%    /usr/var/chroot/named/dev

see how my devices are ad4a instead of ad4s1a?  The missing s1 means
no MBR label.

this is what you need to do, to make the SMD 'a' slice start in sector
0.  (unless you were smart enough not to put your big FTP filesystem
into the 'a' slice).  The installer won't do this type of raw label,
even if you set it to Dangerous Mode, so I expect FreeBSD to try to
resist.  I don't remember how I did it.  definitely ``by hand'' and I
remember some obstinance.

maybe you should back up the first 1MB of the raw unpartitioned disk
before you start.  and for the love of god dont make any ``extended''
MBR partitions on the peecee because this scatters tiny labels all
over the outer reaches of your disk, so the 1MB backup won't protect
you.


or, use Linux.  it ``just works''.  each labeling scheme is a ``kernel
module''.  You can build all the weird modules on Linux/i386, load
them all, and read your Sun disklabel using the Sun disklabel
Interpretation Kernel Module.  It will print a vanity string in dmesg
when it loads:

Ability to Read Sun Disklabels translation module loaded.  [(c) 1998 by darklightw4rriorz at pheerdoom.net]

Then you can download some weird version of fdisk like sunfdisk2-ng or
something, that's able to write Sun disklabels---this will let you
edit the label on the disk, then call an ioctl to load the new label
into the kernel.

BSD has the foundations of a better architecture.  there are ioctls in
bsd to load the in-core disklabel without touching the on-disk label.
There are userland programs to read bsd labels, bsd slices, smd
labels, and mbr labels in BSD, which could be built on non-native
architectures, to read the label and load it into the kernel without
touching the disk.  There is a whole geom framework for doing things
more complicated than simple disklabels.  but in my own experience,
the right command line flags to do what you want just don't exist.
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