In Exchange 2010 after a database availability group (DAG) has been created it is necessary for administrators to add database copies to members. This is generally accomplished using the add-mailboxdatabasecopy command.
When add-mailboxdatabasecopy is run, if the copy is successfully created an online seeding operation automatically occurs. The online seeding operation that occurs utilizes the public / MAPI interface to initially seed the database.
It may be desired in certain instances to have the initial seeding operation occur over one of the private / replication networks defined for the DAG. This is currently not possible since add-mailboxdatabasecopy does not implement the –Network parameter to specify an alternate network be utilized.
You can though work around this and achieve the initial seed over the private / replication network. To do this:
Run add-mailboxdatabasecopy using the –seedingPostponed switch. This will add the copy but not attempt the initial seeding operation. It will also place replication in a suspended state.
Follow this up with update-mailboxdatabasecopy –Network and specify the private / replication DAG network. This will allow the seeding operation to occur over the replication network. Upon successful seed the replication instance will be automatically resumed.