Re: [ECOS] FAT on NOR/ NAND flash

["viren.dobariya" <viren dot dobariya at aftek dot com>]

hi, Ross 
Thanks for your quick response.
But now at primary stage, I want to check that it will work or not.
So plz tell me basic requirement to port FAT on nor flash.

Regards,
Viren


On Wed, 2010-05-26 at 10:58 +0100, Ross Younger wrote:
> viren.dobariya wrote:
> >    I am trying to port FAT on NOR flash of EA2468 board.
> 
> Running FAT on a raw flash device is not a good idea. I would suggest 
> that you use a different filesystem more suited to flash memory parts - 
> jffs2 and yaffs come to mind - or, if you really insist on using FAT, 
> implement a flash translation layer including wear levelling.
> 
> 
> FAT was designed for media with small (often 512 bytes) sectors which 
> are individually rewritable (floppy drives, hard drives); NOR flash 
> devices can only be erased at the block level (64k or more). You'll have 
> an awful lot of trouble making it work properly. Because of this it is 
> also quite dangerous: the length of time taken to erase and reprogram a 
> whole block is much longer than it takes to write a sector to magnetic 
> media, leaving you very vulnerable to power supply issues.
> 
> Furthermore, the filesystem stores its file allocation table at fixed 
> sector locations. This leads to those regions of your flash device 
> experiencing a disproportionate amount of use; they will likely wear out 
> quickly, rendering your filesystem useless.
> 
> 
> Ross
> 
> -- 
> eCosCentric Ltd, Barnwell House, Barnwell Drive, Cambridge CB5 8UU, UK
> Registered in England no. 4422071.                 www.ecoscentric.com
> 


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