I have an Exchange 2013 three node DAG. The servers are Mail 1, Mail 2 and Mail 3. We have several databases on Mail 1 and two are on Mail 3. Mail 2 is reporting a copy queue length of 400 and it is growing for the databases that are on Mail 3.
Does this indicate that the problem is on Mail 2 or Mail 3? What causes a copy queue length?