same mistake: sucessful installation but the partition table is empty -SOLVED

[marmango <marmango@softhome.net>]

>>...
>>
>>What happened is somehow you specified an offset of 0 for the start of
>>the first partition.  Block 0 just so happens to be where the
>>partition table is loaded (along with the MBR).  So, what happens to
>>be where the MBR and partition table is supposed to be got overwritten
>>by the PBR instead (which looks like an empty partition table,
>>curiously.  Hmmm... I wonder what the new PBR looks like.  heh.  Guess
>>I got some testing to do... 8)
>>
>>This is workable, but in general, a bad idea for a few reasons (for
>>one, if someone were to re-install the MBR code on your system -- a
>>usually acceptable and safe proceedure -- your system will be in big
>>trouble).  You *could* leave your system this way, but I would
>>*really* recommend pulling any data and config off the thing and
>>re-partitioning the system.
>>
>>In general, you want to leave the first track unallocated.  In *your*
>>case, your first OpenBSD partition should start at sector 63, not
>>zero.  That comes from your drive's geometry, reported by fdisk:
>>"geometry: 4865/255/63" (it will vary on different drives, BIOSs, and
>>interfaces).
>>
>>More info on what is going on, plus what those annoying TLAs I just
>>threw around meant:
>>  http://www.openbsd.org/faq/faq14.html#Boot386
>>
>>BTW: Good problem report, good details. 8)
>>
>>Nick.
> 
> 
> I' m in the same situation on an old notebook armada without CD drive
> nor NIC...only a floppy :-(
> And because I couldn't make the Cirrus Logic 7548 graphics card work
> under xfree86 (in openbsd that is, haven't tried it on linux yet), I
> decided to remove openbsd keeping the data in the other partitions
> intact, because the only way to backup/restore is through the parallel
> port connection This is the way I worked until now- I used linux to copy
> the installation files in a folder in the ext2 fs. But now I cannot boot
> linux because linux's fdisk sees only the opebsd's partitions (msdos' is
> worse...sees an empty disk like openbsd's).
> There should be a way to restore the MBR into the dos compatible 
> format...I don't care loosing the disklabel...
> My goal is to save the data on the fat32 and ext2 partitions.
> Aggelos. :-\
> PS: I attached output from openbsd's fdisk and disklabel and linux's fdisk
> # /dev/rwd0c:
> type: ESDI
> disk: ESDI/IDE disk
> label: ST91420AG       
> flags:
> bytes/sector: 512
> sectors/track: 63
> tracks/cylinder: 16
> sectors/cylinder: 1008
> cylinders: 2794
> total sectors: 2816352
> rpm: 3600
> interleave: 1
> trackskew: 0
> cylinderskew: 0
> headswitch: 0		# microseconds
> track-to-track seek: 0	# microseconds
> drivedata: 0 
> 
> 16 partitions:
> #        size   offset    fstype   [fsize bsize   cpg]
>   a:  1552320        0    4.2BSD     2048 16384   328 	# (Cyl.    0 - 1539)
>   b:   165312  1552320      swap                      	# (Cyl. 1540 - 1703)
>   c:  2816352        0    unused        0     0       	# (Cyl.    0 - 2793)
>   i:   544257  1717695     MSDOS                      	# (Cyl. 1704*- 2243)
>   j:   552321  2262015    ext2fs                      	# (Cyl. 2244*- 2791)
> Disk: wd0	geometry: 698/64/63 [2814336 Sectors]
> Offset: 0	Signature: 0xAA55
>          Starting       Ending       LBA Info:
>  #: id    C   H  S -    C   H  S [       start:      size   ]
> ------------------------------------------------------------------------
>  0: 00    0   0  0 -    0   0  0 [           0:           0 ] unused      
>  1: 00    0   0  0 -    0   0  0 [           0:           0 ] unused      
>  2: 00    0   0  0 -    0   0  0 [           0:           0 ] unused      
>  3: 00    0   0  0 -    0   0  0 [           0:           0 ] unused      
> Disk /dev/hda: 64 heads, 63 sectors, 698 cylinders
> Units = cylinders of 4032 * 512 bytes


I managed to reconstruct the MBR from the disklabel info, using fdisk.