Currently when using copyoffload migrations the populator log doesn't mention which method it actually used to clone data, ideally we hope offload /xcopy is used however when the source/target are not the same storage or if they don't support xcopy commands cloning reverts to offload's fallback method. 

Populator logs should state which method is expected to be/was used, if we dig around we can find this out however reporting it clearly on logs may help us/customers.