Hi again,

I have a similar problem on my board but I think that I am to blame for it:

On partition on my NANd is normaly used with YAFFS on it. In some cases I unmount that device and make a raw write on it (using ecc
and yaffs oob format). After everything is done I erase the partition and the device can be remounted as an empty YAFFS file system.
In case something goes wong and I try to remount the device YAFFS starts complaining about blocks that are not erased and most of
the devices blocks get marked  as bad. So I have to cheat to get my flash back.

Is there a way to check the filesystem before mounting it. In my case I'd prefer discarding data instead of loosing blocks...

Regards, Stephan

> -----Original Message-----
> From: Charles Manning [mailto:manningc2@actrix.gen.nz]
> Sent: Mittwoch, 23. April 2003 22:18
> To: Paul Wong; yaffs list
> Subject: Re: corrupt my NAND flash device
>
>
> On Tuesday 22 April 2003 19:51, Paul Wong wrote:
> >  Hi all!
> >      i installed the YAFFS file system in the NAND flash (samsung 16MB).
> > And test the reliability. I tried to copy a 5 MB file to the mounted yaffs
> > (spare 8MB) directory ( i separated the device to 3 partition - 4MB 4MB and
> >   8MB) . and then check the disk space, it is shown that it has 3 MB spare.
> >   Next step, I erased the file and copied another 5 MB file to it. The
> > device
> >   said " no enough spare. Then I use the "mkyaffs" to format it, it is
> > shown many bad block in the device. I checked the OOB[5] ( bad block flag)
> > it is set to 0x00. Why? Why the yaffs set the health block to the bad block
> > after
> >   erase file? Is the YAFFS not support big file ?  any ideal?
>
>
> Can you send the output of /proc/yaffs?
>
> YAFFS certianly supports large files and you should not be seeing problems
> like these.
>
> As YAFFS writes data to the NAND it checks the results. If it encounters data
> errors then it marks the block for retirement and you get ""**>>Block %d
> marked for retirement" messages. Later on, during garbage collection, these
> blocks will be marked as bad blocks.
>
> I suggest that while you figure the problem out you first disable the bad
> block marking.  You can do this by commenting out the two lines in
> yaffs_RetireBlock() that write to NAND. Now the software will think these
> blocks have been retired, but the NAND will not be marked.
>
> I have seen this problem before where the NAND read/write algorithms were not
> working properly and YAFFS was thus seeing bad data and thought the blocks
> were bad.
>
> You might, of course, really have a bad chip or bad soldering etc. You should
> not have more than approx 1-2% bad blocks.
>
> -- Charles
>
>
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