Greetings,
I have recently taken over the management of an Exchange 2010 migration that consists of 2 AD sites; one in Boston and one in LA. One DAG with 2 nodes, one in each site and one combo hub/CAS server in each site. All are running Exchange 2010 SP2 with RU6.
The current configuration has the RpcClientAccessServer setting for all 4 mailbox stores set to the CAS server name in LA. However all databases are mounted and active in Boston (which is where they should be mounted). In addition to be incorrectly configured by not leveraging a CAS array, LA is not the primary site; most users will be accessing their mail physically in the Boston location. The ActivationPreference for all mailbox stores also has LA at 1 and Boston at 2, when it should be the other way around.
There are approximately ~500 users/mailboxes in the Org and probably only ~300 have actually accessed their mailbox via Outlook. This is a new Org that is transitioning from an external IMAP server/webmail (not Exchange).
So the concern I have is that the ~300 users now have the LA CAS as their RPC server.
Here is what I would like to do, and I'm reaching out to this forum for a sanity check to see what kinds of issues I might be faced with and also to point out any glaring misconceptions or flaws in the plan.
Step 1: Create a CAS array in both sites ("Outlook" in Boston and "Outlook-DR" in LA for the purpose of this discussion).
Step 2: Create an A record INTERNALLY ONLY for Outlook.somecompany.com and point to the Boston CAS for now since there is only one.
Step 3: Set the RpcClientAccessServer for all 4 stores to outlook.somecompany.com.
Step 4: Change the ActivationPreference for all 4 stores so that Boston is set to 1, LA to 2.
The first four steps above will at least allow new users get the correct RPC point of access. For users who already are pointing to the LA CAS directly the following will be scheduled at some point in the near future:
Step 5: Either manually reconfigure the Outlook client to point to Outlook.somecompany.com or
Step 6: Introduce a second CAS in LA and decommission the original CAS to force the clients to connect to CAS array.
It is the last two steps that I am a bit shaky on. Especially step 6. Will the decommissioning of the old CAS indeed force the Outlook clients to automagically find the CAS array?
Additionally, in the interim before I do either step 5 or 6, will changing the ActivationPreference break anything for users with existing Outlook profiles?
Thank you in advance for your consideration!
JC