[Yaffs] Are Yaffs partitions vulnerable?

Hi,

I have a problem with the data integrity on Yaffs partitions:
It looks like this:

If I
- initialize 2 Yaffs partitions and mount them
- generate a file on each partition
- unmount the partitions
=> next mount, everything OK

But if I
- initialize 2 Yaffs partitions and mount them.
- generate a file on each partition
- shutdown the system an restart WITHOUT unmounting
the Yaffs partitions
=> next mount: Yaffs scans the partitions and comes
out with various results:

- either the files are gone (not even there in lost+found)
- or the files have a name comprised of 254 0xff characters

If I just read a file (instead of generating it anew each
time) it happens, that the file is still there, but not always.

Is Yaffs that vulnerable through improper shutdown? Note, that
I do not switch off power at an undefined time yet. I just
use my debugger to restart my system before the shutdown
procedure (which would write the checkpoint).

Any help would be greatly appreciated!
Thanks,
Gerhard