front-end block device behavior in solaris guest (b44)

Description:

I noticed that if i pass a disk partition (phy) through to a solaris guest, the guest sees the whole disk rather than the specific partition handed through. example:

disk = [ 'phy:sdb3,5,w' ]

with this example, other guests (NetBSD, various linuxes) front end block driver presents the sdb3 partition as a "virtual disk", which can then be partitioned, etc as if it were a complete disk. the solaris xvbd, however, presents all of sdb to the guest, rather than just sdb3:

# devfsadm -c disk -i xvbd
# ls /devices/xendev/xvbd@5*
/devices/xendev/xvbd@5:a        /devices/xendev/xvbd@5:k,raw
[...]
# fdisk /dev/rdsk/c0d5p0
                Total disk size is 3149 cylinders
                Cylinder size is 4096 (512 byte) blocks
                                                                         Cylinders
        Partition    Status      Type                   Start      End     Length        %
        ======    =====      ===========   ====      ===     =====     ====
              1        Active       Linux native              0         62          63            2
              2                        Linux native             62     1658       1597          51
              3                        Linux native          1659     2172         514         16
              4                        EXT-DOS             2172     3148         977         31
[...]

Is this expected behavior, or is it a bug?
tia,
Sherry
ps: i'm using a redhat dom0 on Xen 3.1

Explanation:

There could be some stale fdisk info on sdb3 which is read and
interpreted in Solaris domU.
Please try to clear the first 8k space on sdb3 by dd'ing '/0' to it,
then try it again.

Discussion:

Your suggestion worked (dd if=/dev/zero of=/dev/sdb3 bs=1K count=8). i didn't notice that the size of the disk reported was correct (it was the size of the partition handed through), however as you pointed out, fdisk was getting confused about some data in the first 8K.

i went ahead and used fdisk to create a solaris2 partition for the whole "disk" (100%), and then had fun creating slices using fmthard. luckily, our CTO is an old unix hack who helped me ensure the slices fell on cylinder boundaries. is there a more user-friendly way to create slices on a x86 disk partition than fmthard?


Yes. You may want to use 'format', then choose the disk you want to
create slice on by inputing the number with it, then input 'partition'
command. OK, now you can see the menu to play with partitions(slices).
Don't forget to use 'label' command to flush all your changes onto the
disk(virtual disk), when you're done ;-).