> > I have a usb flash drive that I wish to reformat as an MS-DOS (FAT) file
> > system. How do I do that on OpenBSD?
>
> For interactive MBR edits you can use "fdisk -e sd0"
> You probably want to use "0C" for FAT32 with long file name support.
I recently bought several flash drives and tested them out on my friends'
Windows machines and Macintoshes. The factory-installed MBR partition
tables vary dramatically between drives. But if the drives are
reformatted, then they will have MBR partition tables similar to the
following.
Disk: sd0 geometry: 492/64/32 [1007616 Sectors]
Offset: 0 Signature: 0xAA55
Starting Ending LBA Info:
#: id C H S - C H S [ start: size ]
------------------------------------------------------------------------
0: 0B 0 1 32 - 491 62 7 [ 63: 1007496 ] Win95 FAT-32
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
When reformatting a drive, both Windows machines and Macintoshes produce
identical partition tables for any given drive, so this clearly sets a
precedent: the id entry in the table should be "0B" for maximum
compatibility.
I did encounter something odd, though. On every Macintosh-formatted
drive, fsck_msdos complains that "FAT starts with odd byte sequence", and
offers to fix the problem. But regardless of whether or not I choose to
fix it, the problem is still there the next time I run fsck_msdos. Does
anybody know what's going on?
