Exchange '10 Multi-Site/SAN Design Across WAN

If bandwidth isn't an issue, your offices abroad should be connecting to their mailboxes at the main site via OA over the internet. I'm guessing that because they have to VPN that you don't have a direct IP route between the remote sites and the main site. But if you don't have that already, then how would you be running backups/DAG replication between these sites? I'm a bit confused about that.

However, if you have IP connectivity, and if you want to drop additional CAS/HT/MBX into the remote offices, it's doable. Put the DBs for RemoteA on the MBX role in RemoteA, same with RemoteB and their stuff on their server, and DAG them all back to the main office MBX servers. DAG the main office DBs to the remote office servers, too.

HT will sort itself out, really, just make sure you add the new HT servers to some new send connectors that look just like the one you already have.

For CAS, there's a powershell command you'll run against each of the new DBs you make, to set the RPCClientAccessServer to the appropriate value. But your OWA/OA/AS will still just be at the main office CAS.

Once you do this, and you have each DB on four servers in the DAG, you can stop doing backups. Set circular logging on the DBs and relax.

Bandwidth is an issue as some offices are limited in that country and Internet bandwidth is pretty expensive. In terms of routing would everything still have to hit the main production Exchange server (based on the MX record) and then get forwarded out to the appropriate DAG DB? Or would it simple make a "copy"?

If you're talking about one email domain, all the mail will come into the primary MX record. The HT role will pick it up from there, and deliver it to the correct MBX server/active database, possibly through other HT servers as necessary.

Then, the active DB ships the transaction logs back to every other server that holds a passive copy of that DB. Since bandwidth is an issue, this would be a double whammy.

Sounds like you want to keep all your Exchange in one location, and have those remote office users connect to their mailboxes over the internet, either with OWA, or with Outlook only if you have some serious transport and mailbox size caps in place.

Actually quite the opposite, would like to only keep Exchange servers where the according SGs/users are however, the concern is for backups, which are all done at one location.