[Yaffs] Fwd: nand erase

    I have two questions.
1)    Is there any tool which can take nand erase,scrub,rw test tools  in
linux os?
       I am using mtd utils,but there is no erase and scrub option.
2)    First ,I can mount yaffs on nand mtdblock.
       Secondly, several nand block oob is flushed to all 0 bytes for
unknow reasons.
       Thirdly,I mount yaffs on the nand mtdblock, it says" bad block is
found",but mount succeeds.
       Finally,I copy files to the mount point, it syas"**>> yaffs chunk
1075 was not erased"etc.

       How could I make the nand flash to normal stat?

        I beg for your suggestions,thanks!