I assume you’re using FOG 1.2.0 ?
The first thing to make sure of, since you want two INDEPENDENT storage nodes (non - replicas of each other), both storage nodes need to be inside their OWN storage group. They can’t be in the same group, it’ll only create problems down the road (for your specific desires).
Set both as the master node of their storage group.
Can you verify that the new storage node’s credentials are set correctly? https://wiki.fogproject.org/wiki/index.php/Troubleshoot_FTP#Credentials_.2F_Passwords
Also, you might wanna look into FOG Configuration -> FOG Settings -> Storage nodes. Those two fields are for the FTP user and pass, which would be the same since your 2nd storage node is local…
You may also wanna look at how you’re mounting the USB disk with in /etc/fstab and make sure you’re mounting in a way that includes full permissions (read and write).