yaffscmd <volname> {bad | info | markbad | erase | format}

[root@sylixos:/root]# help yaffscmd       
eg. yaffscmd n0 bad         show volume "n0" bad block.
    yaffscmd n0 info        show volume "n0" information.
    yaffscmd n0 markbad 3a  mark block 0x3a is a bad block.
    yaffscmd n1 erase       erase volume "n1"
    yaffscmd n1 format      format volume "n1"
yaffscmd volname [{bad | info | markbad | erase | format}]
[root@sylixos:/root]# 

[root@sylixos:/]# cd /yaffs2/
[root@sylixos:/yaffs2]# ls
n0  n1
[root@sylixos:/yaffs2]# yaffscmd n0 info
Device : "/n0"
startBlock......... 1
endBlock........... 128
totalBytesPerChunk. 2048
chunkGroupBits..... 0
chunkGroupSize..... 1
nErasedBlocks...... 127
nReservedBlocks.... 10
nCheckptResBlocks.. nil
blocksInCheckpoint. 1
nObjects........... 4
nTnodes............ 0
nFreeChunks........ 8128
nPageWrites........ 0
nPageReads......... 0
nBlockErasures..... 0
nErasureFailures... 0
nGCCopies.......... 0
allGCs............. 0
passiveGCs......... 0
nRetriedWrites..... 0
nShortOpCaches..... 10
nRetiredBlocks..... 0
eccFixed........... 0
eccUnfixed......... 0
tagsEccFixed....... 0
tagsEccUnfixed..... 0
cacheHits.......... 0
nDeletedFiles...... 0
nUnlinkedFiles..... 0
nBackgroudDeletions 0
useNANDECC......... 1
isYaffs2........... 1

[root@sylixos:/yaffs2]# yaffscmd n0 bad
[root@sylixos:/yaffs2]# yaffscmd n0 markbad 54
yaffs: marking block 84 bad
mark the block 0x54 is a bad ok.
[root@sylixos:/yaffs2]# yaffscmd n0 bad
block 0x54 is bad block.
[root@sylixos:/yaffs2]# yaffscmd n0 erase
Erasing...
 128 /  128
yaffs volume erase ok
[root@sylixos:/yaffs2]#