Invalid partition table after sysinstall modifications

[Doug Poland]

Warren Block said:
> On Sat, 22 May 2004, Doug Poland wrote:
>
>> I've got a 4.9-STABLE system that was dual-booted between FBSD and
>> Win2K.  I had no further need for the windows slice so I used sysinstall
>> to delete the NTFS slice, write it as type 165, newfs'd it, mounted it,
>> and wrote a bunch of data to the new ufs slice.  So far so good...
>> About 8 hours after this procedure the system hung, I rebooted and
>> received the message,
>>
>>    "Invalid partition table"
>>
>> I was able to boot the system with a FreeSBIE live bootable CDROM and
>> fsck all the ufs slices.  The data on all slices appear to be good, but
>> I cannot figure out how to get this box to boot again.  I've google'd
>> and read the appropriate handbook sections.
>
> Hmm.  It looks like that error comes from the plain mbr code
> (/boot/mbr), not the boot-selector loader (/boot/boot0).  The plain mbr
> only wants one partition (slice) to be active.
>
> See what fdisk has to say about your partitions.
>
djp at FreeSBIE:~/djp# fdisk /dev/ad0
******* Working on device /dev/ad0 *******
parameters extracted from in-core disklabel are:
cylinders=119150 heads=16 sectors/track=63 (1008 blks/cyl)

Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=119150 heads=16 sectors/track=63 (1008 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 22 (0x16),(OS/2 BM: hidden DOS with 16-bit FAT (>= 32MB))
    start 63, size 4096512 (2000 Meg), flag 0
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 254/ head 254/ sector 63
The data for partition 2 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 4096575, size 20964825 (10236 Meg), flag 80 (active)
        beg: cyl 255/ head 0/ sector 1;
        end: cyl 1023/ head 254/ sector 63
The data for partition 3 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 25061400, size 95040540 (46406 Meg), flag 80 (active)
        beg: cyl 1023/ head 255/ sector 63;
        end: cyl 1023/ head 254/ sector 63
The data for partition 4 is:
<UNUSED>

I'm not sure what we're looking for here.

-- 
Regards,
Doug