I just don't understand these "copyright" issues your having. If you're logged in as root you should not have any permission issues copying/rsyning the files.
How are you accessing the Zimbra server? From a windows machine using putty?
Can you run the following command (replacing /path/to/usb with the mount path of the usb drive):
Then can you post the exact output of the command here.Code:rsync -aHK /opt/zimbra /path/to/usb