Linux installs on CF Flash chips.

[Peter Arremann]

On Thursday 30 June 2005 23:08, Jim Cornette wrote:
> Having an installation of Linux on a CF Flash, I am wondering if it is
> needed to check for bad blocks during file formatting. I am also
> wondering if using tune2fs -c 0 and tune2fs -i 0 is needed or is a bad
> idea. I did not set up this CF installation, but am curious as to CF
> Flashes and their reliability.
> The options they used were for tune2fs and formatting the filesystem with
>   mkfs.ext2 -j /dev/hda
> Would passing the -c flag to mkfs.ext2 along with the -j option for
> journalling be needed for flashes? Will it mark the blocks as bad before
> the filesystem is used for anything?
Flash memory has a limited number of cycles before it goes bad... Somewhere 
between ten thousand and 10 million, depending on the manufacturing process 
and design. Check with your manufacturers specs for that. 

All traditional filesystem layouts are known to re-write the same sectors over 
and over again - super blocks, inodes and so on. They are less than ideal for 
flash memory because of that - they'll wear out some memory blocks real fast 
while most of the rest is still fine. 

Because of that, special filesystems like JFFS(2) have been developed that 
take the rewrite cycles into account and make your CF card last much much 
longer. For more info, this page 
http://linuxdevices.com/news/NS7386103729.html has some pretty good 
information. 

Peter.