I'm looking at deploying a stretched DAG across two datacenters.
2 servers - CA/HT Role
2 mailbox servers (Active Database copies)
1 server - CA/HT role
1 mailbox server (Passive Database copies)
1. Can the Witness Server reside on one of the CAS servers?
2. Is a Witness Server required at the Failover DataCenter?
3. The examples that I have seen have always had at least two mailbox servers at the Failover site, is this design valid?