Re: [gentoo-user] Strange partition on USB stick

[Mick]

On Tuesday 04 Oct 2011 20:36:06 Paul Hartman wrote:
> On Tue, Oct 4, 2011 at 1:39 PM, Mick <michaelkintzios@×××××.com> wrote:
> > On Tuesday 04 Oct 2011 17:18:18 Paul Hartman wrote:
> >> You can create a real partition table on that device and reformat, if
> >> you want. (Note that some flash-based devices suffer degraded
> >> performance if you repartition or reformat them because they come with
> >> specially-aligned FAT tables from the factory)
> >
> > Interesting!  I didn't know that.
> >
> > I have repartitioned USB sticks in the past, but did not notice any
> > change in performance - to be honest I didn't measure it.  I assume then
> > that if I were to re-partition for any reason I would need to stick to
> > exactly the same start & finish shown by parted.
> >
> > Re-formatting it ought to be OK though, as long as the fat16 shown by
> > parted is correct.
>
> I think filesystems other than FAT are aligned well already, assuming
> your partitions are aligned, but with FAT there are some hoops you
> must jump through.
>
> There is a tool called flashbench that can test your drive
> (destructively!) and figure out the most optimal block sizes. Here's a
> great article about it and optimizing USB flash drives in general:
> https://lwn.net/Articles/428584/
>
> And here is a forum thread about figuring out the FAT alignment:
> http://www.patriotmemory.com/forums/showthread.php?3696
>
> The SD council makes a tool for MS Windows that optimally formats and
> securely erases SD cards. Might be interesting to compare the results
> of its format to a standard fdisk and mkfs.vfat in linux.
>
> One thing I'm going to do next time I get a new SD card or flash drive
> is take a snapshot of the boot sector/partition tables/FAT tables so
> if I ever want to reformat it to FAT, I can restore the -- presumably
> optimal -- factory layout.

Excellent find!  I've got some studying to do. 

Thanks for sharing.  :-)
-- 
Regards,
Mick