I have a client that has exploded in size over the past year. They currently have a single Exchange 2010 server with all roles. Currently about 400 mailboxes and 900gb of mail. Growing approx 300GB/4 months. The server has 4 virtual cores, 12gb ram. They are in our hosted environmental and all users connect via RPC/HTTPs or OWA.
They have ok’d 2 more servers and rebuilding the current one to remove some latent issues. I am trying to figure out the best layout of the servers and have come up with 2 options:
1. 1 CAS server with 2 Database server. Servers would have DAGs between them and the primary/secondary split based on size for each DB
2. 2 CAS servers with 1 DB server. Create DAGs between the DB and CAS servers and have the CAS have half of the databases in secondary mode.