Set this policy to define the max cache size Delivery Optimization can utilize as a percentage of the internal disk size.
The policy is located under Machine of Local Group Policy Editor.
* Making mistakes while changing registry values can affect your system adversely. We recommend you to create a System Restore point before making registry manipulation. If you're new to Registry Editor, read this beginner's guide.
** To locate the registry and administrative template path, checkout beginner's guide.