[Flashbench] Results for Sandisk class 4 "SDHC card"

[Arnd Bergmann]

Hi Sascha,

Thanks for your measurements. The results are highly unusualm and definitely require more
research. Especially the 512 KB erase block is strange, so it's quite likely that there
is something more going on.

On Saturday 02 April 2011, Sascha Silbe wrote:
> 
> Size: 3965190144B = 3872256 KiB

The size is a very good first indication: It is not a multiple of full megabytes,
but a multiple of 1.5 MB (2521 time 1.5 MiB). For a card produced in 2010, that
means it's quite likely to actually be based on 1.5 MB erase blocks.

This is not well supported in flashbench, but what you can try is pass a blocksize
and erasesize that are a multiple of three:

flashbench -a /dev/mmcblk0 --blocksize=1536 --count=100
flashbench --open-au --open-au-nr=5 --erasesize=$[1536 * 1024] --blocksize=1536 /dev/mmcblk0

When you have the correct erase block size, the results of the other tests
should make much more sense.

	Arnd