Multi-Site Exchange 2010 Question


I have Exchange 2010 configured in (2) separate sites, each site with its own datacenter.

In each site, I have a DAG with (2) members, a CAS-Array with (2) members, and a hardware load balancer.

For the most part, I have users setup so that if they are in site 1, their mailbox is in the site 1 DAG.  Likewise, if they are in site 2, their mailbox is in the site 2 DAG.  

However ... we sometimes run into issues where a user is physicall located in site 1, but their mailbox is in site this instance, considering that the Exchange DAG properties tells the database that it's CAS-Array is set to be the CAS-Array in site 2, the user connects to the CAS server in site 2 (even though the user is physically located in site 1).

Is there any way to get the user to connect to the local CAS server in site 1 in order to use their mailbox in site 2?  Is this even worth it?  Does it make a difference for a user to connect to a local CAS server that will access a mailbox in a database that lives in another site?

I was also wondering ... if there was NOT an Exchange database in a physical site and all users in a remote site connected across a WAN link / VPN to access all Exchange resources in a main datacenter, but the remote site had physical infrastructure that COULD support a CAS server, would it help the site at all to have a local CAS that could take connections from Outlook and other desktop calls and send them to the database server at the main datacenter ... or is this a silly thought, and are things best left accessing them across a WAN link?

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Amit KumarCommented:
Simple thing, wherever user is homed user will connect only to that site.

your CAS server on site-1 can only redirect or proxy requests but user always connects to homed mailbox server which is in either sites.

Now it does not matter as long as you have good connectivity between both datacenter so user can connect to any site wherever user sit. Notifiable thing is if in any case your network is getting problem in case of high bandwidth high utilization.
Miguel Angel Perez MuñozCommented:
CAS connections are defined at database level. Every database has defined CAS used. Your issue (or requirement) is user uses other CAS different that has database configured. This can not be done, you must move user from database to another database has CAS you are trying to use configured.

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