NAND +concatenation

Hi,

I am being a bit thick today & cannot quite understand if I am doing this right...

I have 4 64MB NAND chips, I can get the MTD concatenation to add them to a single device (6) which is defined as having one partition.

How can I use this single device ?

Should I be able to "flash_eraseall -j /dev/mtd6 " ?, this returns a "/dev/mtd6: Bad block check not available" error.
or do I need to format each chip in turn ?

Also should I be able to mount this single device as a formatted filesystem ? "mount -t jffs2 /dev/mtdblock6 xxx"

Thanks for any advice.

Neil