[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: JFFS2 on NAND flash



On Thursday, 31. January 2002 15:30, David Woodhouse wrote:
> You can't do it like that. What if you lose power while the block is
> erased, but before you have written the data back again? You lose all the
> information from the remainder of that erase block.
I realized this already. 

On Thursday, 31. January 2002 15:30, David Woodhouse wrote:
> I think you get away with it on JFFS1. You don't have nodes small enough
> that you'll fit ten of them in a page, and you can go for a couple of weeks
> without the lack of ECC biting you.

You talk about ten nodes. The Toshiba datasheet says, the maximum is 3 
consecutive writes to a page before erase. The Samsung datasheet talks about 
2.
jffs1 does up to 10 and jffs2 up to 12 consecutive writes on a page. I saw 
these maximums on a 30 min test, where i was copying files to jffs1 and jffs2 
and removing them afterwards. So both exceed the datasheet maximum.

Tonight i setup a test on two boards. One having JFFS1 and one JFFS2. The 
write verify flag for NAND is enabled on both boards.
The test procedure was the same on both boards:

cp -R /tst /nfs/tmp

while diff -r /tst /nfs/tmp/tst
do
cp -R /tst /mnt/tmp
rm -Rf /nfs/tmp/tst
cp -R /mnt/tmp/tst /nfs/tmp
rm -Rf /mnt/tmp/tst
done

Result:
JFFS1:	
script stopped after 480 cycles.
After reboot and mounting:
JFFS: Failed to build tree
JFFS: Failed to mount device 1f:02

JFFS2:
script run all night
After reboot and mounting:
At mount time JFFS2 complains about a bunch of inodes.
Inode #121947 was a directory with children - removing those too....
Cannot remove child "Main.txt", ino #0, because it doesn't exist.
.....
The other files and directories on the partition are ok.

Thomas
__________________________________________________
Thomas Gleixner, autronix automation GmbH
auf dem berg 3, d-88690 uhldingen-muehlhofen
fon: +49 7556 919891 , fax: +49 7556 919886
mail: gleixner@xxxxxxx.de">http://www.autronix.de  

To unsubscribe from this list: send the line "unsubscribe jffs-dev" in
the body of a message to majordomo@xxxxxxx.com