Office 365 – The Big Build Part 2 – MRSProxy

In Part 1 we reviewed the overall configuration of the migration I am working on. As I noted in that post my configuration includes a fully deployed Exchange 2010 environment designed for high availability, which isn’t detailed in any of the build guides. There really isn’t much difference between the build guide for 2003/2007 and my deployment. To recap my 2010 environment consists of:

• 2 CAS/HUB servers using NLB for my CAS Array
• 2 Mailbox Servers with a single DAG hosting 2 Databases
  • 1 Public Folder on a single Mailbox server (MBX1)

The first thing we need to look at is the MRSProxy configuration. The build guide states:

1. On the coexistence server, open the following file with a text editor such as Notepad. <Exchange Installation Path>\V14\ClientAccess\ExchWeb\EWS\web.config
   
2. Locate the following section in the web.config file:
   

   <!– Mailbox Replication Proxy Service configuration –>
   

   <MRSProxyConfiguration
   

   IsEnabled=”false”
   

   MaxMRSConnections=”100″ DataImportTimeout=”00:01:00″ />
   

3. Change the value of IsEnabled to “true”.
   
4. Save, and then close the web.config file.
   

Here is where we need to make some modifications to the build guide. First, this change needs to be made on ALL of your CAS servers and the change should match exactly on all servers. Second, the ‘DataImportTimeout’ value of 1 minute is the default which isn’t enough time for O365 to establish an appropriate connection. Now, this is up to your preference, I’d recommend nothing less than 5 minutes, but in my case I set it to 20 minutes just to be safe. Finally, and most importantly, once you change these settings and save the web.config file you need to restart both IIS and the Microsoft Exchange Replication service. Once completed your web.config file should look like this:

If you don’t make the changes listed above to the default values you will see these types of errors when you attempt to do a remote mailbox move:

 
Stay tuned, in my next post I’ll discuss the Public folder Free/Busy configuration and how the build guide is misleading as to where this folder needs to reside.