I have 2 exchange servers 2010 on a DAG. Second exchange server is in remote location but on same site in AD. Primary site A has all mailboxes replicated to site B. Site A exchange CAS role got corrupted with SP3 install so rolled back to sp2. Now all clients go to site B for CAS. 100MB connection between site A & B. So I created new exch2010 in site A with all patches and SP3. I like to move all mailbox and decommission the old exch2010 in site A.
Site A old exch2010 with SP2 (needs to be decommissioned, CAS not working )
Site A new exch2010 with sp3
Site B old exch2010 with sp2
Can someone can give me step by step instructions to move mailboxes, updated mx records, update CAS array roles etc.??
Also should make this new exch server a part of DAG and replicate first?? what should be the best course of action.