Invalid fdisk partition table found (fwd)

[Warren Block]

On Sat, 26 Nov 2011, Robert wrote:

> Some difference today. Not sure at what point this happened but one of
> my CF cards now reads:
>
> [robert at dell64] ~> fdisk /dev/da1
> ******* Working on device /dev/da1 *******
> parameters extracted from in-core disklabel are:
> cylinders=2057 heads=255 sectors/track=63 (16065 blks/cyl)
>
> Figures below won't work with BIOS for partitions not in cyl 1
> parameters to be used for BIOS calculations are:
> cylinders=2057 heads=255 sectors/track=63 (16065 blks/cyl)
>
> fdisk: invalid fdisk partition table found
> 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 165 (0xa5),(FreeBSD/NetBSD/386BSD)
>    start 63, size 33045642 (16135 Meg), flag 80 (active)
> 	beg: cyl 0/ head 1/ sector 1;
> 	end: cyl 8/ head 254/ sector 63
> The data for partition 2 is:
> <UNUSED>
> The data for partition 3 is:
> <UNUSED>
> The data for partition 4 is:
> <UNUSED>
>
> Now showing 16GB but still not right.
>
...
> I also did this in single user with the same results. Ideally, I would 
> like to change these cards to FAT32 but I cannot get there with fdisk 
> and am not sure how to get there with gpart or if I can.

Creating an MS-DOS layout with gpart(8), where the disk is da0:

# gpart destroy -F da0
da0 destroyed
# gpart create -s mbr da0
da0 created
# gpart add -t "\!11" da0
da0s1 added

11 is 0x0b, the FAT32 partition type.  There might be a more mnemonic 
string for it, this is the first time I've ever used gpart for FAT32. 
The exclamation is for gpart/GPT, and the backslash is to keep the shell 
from messing with it.

# gpart show da0
=>      63  15662997  da0  MBR  (7.5G)
         63  15662997    1  fat32  (7.5G)

# ls /dev/da0*
/dev/da0	/dev/da0s1
# newfs_msdos -F32 /dev/da0s1

fdisk(8) may be easier, just set the partition type to 11.

> I haven't had any luck with the second CF card as it still show 29MB. 
> I will try some more later today or tomorrow.

What happened to make the one card show 16G?