[Discuss] usb thumb drive

[cra at WPI.EDU (Chuck Anderson)]

On Mon, Feb 13, 2012 at 09:58:42AM -0500, Matthew Gillen wrote:
> I got a new thumb drive, and I decided to check it out on my linux box
> before using it.  Fdisk shows this:
> 
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sdb1   *        8064    31293439    15642688    c  W95 FAT32 (LBA)
> 
> I thought the start block being so high we sort of odd.  I know that the
> version of fdisk with Fedora 16 seems to be showing more than it used to
> (i.e., the start block is usually now 2048 instead of 0, I'm assuming
> that means it is representing the MBR where it did not in the past).

No, everyone used to start their partitions at 63 (track 1 for a
63-sectors-per-track disk).  The reason for the switch to 2048 (1MB)
was for erase block alignment on SSDs.  Windows 7 does this too.

> So the 2048 start block is what I expect.  If my calculations are
> correct, this drive has 1909 blocks / MB, so there appears to be about
> 3MB of unused space before the first partition.
> 
> Using dd to copy this sdb2 device to a file then opening it in a
> hex-editor shows that the partition is all zeros.
> 
> Is there a legitimate reason for what I'm seeing?  Are they just leaving
> some space for re-mapping bad sectors?  Why not do that at the end of
> the drive?

No idea why it started at 8063.  What are the CHS values in the
partition table?  Sometimes USB flash memory has weird CHS settings.