Hi Martti
The admin backup command copies the CA Clarity PPM installation directory into a backup directory
This will not ZIP the files just create another folder with the Clarity files (in package.jar and other jars) with a possibility to restore it to previous state. It's designed to provide an automated backup option for files before upgrade on Production servers. So say you have an issue you could quickly revert.
I recommend zipping and moving the Clarity files because 1. admin backup was not exactly designed for moving files between servers, and 2. zipping prevents the binary files from corruption on copying from server to server. (as opposed to just moving entire folder copy)
I hope this helps -Nika