16GB USB Drive Not Accessible

Christopher A. Williams chriswfedora at cawllc.com
Tue Oct 28 11:40:41 UTC 2008


On Tue, 2008-10-28 at 00:23 -0500, Robert Nichols wrote:
> Christopher A. Williams wrote:
> > I recently bought a snazzy new 16GB USB pen drive from the local store -
> > it was only $29! I have several drives that are 8GB and smaller from the
> > same store that are the same brand.
> > 
> > Imagine my surprise when:
> > * The 16GB drive is not accessible on either F9 or F10 Snap 3
> > * The 8GB drives all work just fine on both F9 and F10 Snap 3
> > * The 16GB drive works fine on Windows XP
> > * The 16GB drive also works on a Windows XP VM running on top of F9!!!
> > 
<snip...>
> I've seen several USB pen drives with inconsistent partition tables,
> such as a CHS geometry that leaves a few unallocated sectors (no great
> surprise) but a partition with a sector count that goes beyond the
> claimed last cylinder and does use the entire device.  Automount is
> deliberately made sensitive to such anomalies.
> 
> Take a look at what "fdisk -l" and "fsck.msdos" have to say about the
> drive.  Errors such as "Partition has different physical/logical
> endings" should be cause for concern.  You might need to repartition
> the device and/or rebuild the filesystem.

Thanks - This made complete sense to me - and you were right! Here's the
output of fdisk:
Disk /dev/sdb: 16.0 GB, 16039018496 bytes
75 heads, 40 sectors/track, 10442 cylinders
Units = cylinders of 3000 * 512 = 1536000 bytes
Disk identifier: 0xc3072e18

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1       10443    15663084    c  W95 FAT32 (LBA)

...And here's a summary of what fsck.msdos said:
dosfsck 2.11, 12 Mar 2005, FAT32, LFN
There are differences between boot sector and its backup.
Differences: (offset:original/backup)
  0:eb/00, 1:58/00, 2:90/00, 3:4d/00, 4:53/00, 5:44/00, 6:4f/00, 7:53/00
  , 8:35/00, 9:2e/00, 10:30/00, 12:02/00, 13:10/00, 14:24/00, 16:02/00

...

  , 497:74/00, 498:0d/00, 499:0a/00, 505:ac/00, 506:cb/00, 507:d8/00
  , 510:55/00, 511:aa/00
1) Copy original to backup
2) Copy backup to original
3) No action
? 

...followed by messages about cluster size mismatches, and the like.

So I repartitioned and re-formatted the drive (had to use my Windows XP
VM for that - see question below), and voila!

Now, one last question: what's the flag to format a FAT32 partition with
mkfs? I saw options for pretty much everything but that. I'm probably
just suffering from not having had my first cup of coffee... :)

Cheers,

Chris

--
==================================
By all means marry;
If you get a good wife, you'll be happy.
If you get a bad one, you'll become a philosopher.

--Socrates




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