This was my reply to another topic concerening RSYNC, not sure if it will help you or not, b ut this is how I do it.
Not sure if anyone here has another NAS to backup to (Or a Linux PC) but I had a Seagate GoFlex 3tb. I used SSH to get into tthe Seagate drive and wrote a pretty basic shell script using rsync to backup the critical directories of my WD EX2. Unfortunately I cant run this from cron because I cant put my public key on the WD EX2 without compiling my own version of their firmware, thus I have to start it manually and answer the password request.
rsync -avzW -e ssh firstname.lastname@example.org:/mnt/HD/HD_a2/sourcedir/ /mnt/eSata/.users/admin/targetdir/
If both drives are on your local LAN you can get higher throughput (Approximately 5X) by using the following options;
rsync -aPW --exclude=.wdmc --progress -e “ssh -T -c arcfour -o Compression=no -x” email@example.com:/mnt/HD/HD_a2/SOURCEDIR/ /mnt/eSata/.users/admin/TARGETDIR/
Obviously you would need to fill in the IP address with the IP of your WDNAS and change the source and target directory paths for your application.