How can I take backup of NAND memory?

Create sdcard with any linux distribution like Debian or Fedora. Boot from sdcard and run this command

# dd if=/dev/nand conv=sync,noerror bs=64K | gzip -c -9 > /nand.ddimg.gz

You can restore it using command

# cd / ; gunzip nand.ddimg.gz; dd if=/nand.ddimg conv=sync,noerror bs=64K of=/dev/nand 

 

How can I take backup of NAND memory?