Re: [RAUC] NAND flash

[Enrico Joerns <ejo@pengutronix.de>]

Hi Caglar,

On 04/05/2017 03:10 PM, caglar.kilimci@accenture.com wrote:
> Hello,
>
> I have a question about storage type, NAND. The documentation [1] emphasizes not to use NAND flash but why?
>
 > [1] http://rauc.readthedocs.io/en/latest/updating.html?highlight=nand

well, this is a general advice, not something RAUC-specific. RAUC can 
handle NAND on the different layers, either for writing raw data with 
`nandwrite` or by using 'NAND-filesystems' such as UBI(FS).

But, from ours and others daily experience and knowledge about the 
technology the general conclusion is that raw NANDs, especially MLCs, 
are very, very hard to handle.
There are many different and hardware-specific effects that you have to 
deal with, and if you see how hard for example developers from the UBI 
filesystem attempt to solve this, [1] you may also conclude that you 
really want to avoid using NANDs on this level.

Our advice instead would be to use eMMCs instead, where all the critical 
stuff is hidden and handled internally, by hardware-controllers designed 
by those who (hopefully) really know about the quirks of their NAND chips.


I hope I could make that point a little clearer, I know that this 
documentation chapter is not our most extensive one, yet. Patches are 
always welcome ;)


Best regards

Enrico


[1] 
http://free-electrons.com/pub/conferences/2016/elce/brezillon-ubi-mlc/ubi-mlc.pdf

-- 
Pengutronix e.K.                           | Enrico Jörns                |
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