DPM will not see passive copies and\or nodes when the replication writer is disabled. If you find missing components during enumeration please check the following potential causes.
1) The agent is not installed on any of the nodes that owns the mailbox database attempting to be protected. If this is the case, ensure that an agent is installed on the node that holds the Mailbox database you are attempting to protect.
2) The EnableVSSWriter regkey is set to 1 under HKEY_LOCAL_MACHINE\Software\Microsoft\ExchangeServer\v14\Replay\Parameters\EnableVSSWriter. If this is the case, check all nodes of the DAG and ensure that the registry does not exist, or if it does, that EnableVSSWriter is not set to 1. If you make this change, remember to restart the Exchange Replication Service for it to take effect.
3) There are VSS errors causing the datasources not to enumerate. If so, verify that all Exchange Node and Exchange VSS components are functional.
- Ensure all databases are mounted and healthy
- Run vssadmin list writers – Check to see if the Exchange Writer is in stable state
- Review System event log for VSS or Volsnap errors