new-mailboxexportrequest fails – TimeoutErrorTransientException

Sometimes when you do a new-mailboxexportrequest you receive the following error:
The call to 'net.tcp://prexchu01/Microsoft.Exchange.MailboxReplicationService PREXCHU01.******** ( caps:0 7)' timed out.

Error details: This request operation sent to net.tcp://prexchu01/Microsoft.Exchange.MailboxReplicationService
did not receive a reply within the configured timeout (00:01:00). The time allotted to this operation may have been a portion of a longer timeout. This may be because the service is still processing the operation or because the service was unable to send a reply message. Please consider increasing the operation timeout (by casting the channel/proxy to IContextChannel and setting the OperationTimeout property) and ensure that the service is able to connect to the client.

+ CategoryInfo : NotSpecified: (0:Int32) [New-MailboxExportRequest], TimeoutErrorTransientException

+ FullyQualifiedErrorId : C857038,Microsoft.Exchange.Management.RecipientTasks.NewMailboxExportRequest

I have found that it is because the CAS server is located behind a hardware load balancer. We are using a BIGIP load balancer for all our CAS/HUB functions. If you do a get-mailboxdatabase on the database of the mailbox you are trying to move, you will probably see that the RpcClientAccessServer is set to point to the VIP of the CAS pool instead of the actual CAS server.

I have found two ways to fix this, the first (not recommended) is to do a set-mailboxdatabase and set the RpcClientAccessServer to the UNC for the CAS server you are going to use for the export request. Make sure you change it back after you make the change.

The second way, and the way I recommend is to modify the HOSTS record on the CAS server so that the UNC found in the RpcClientAccessServer points to the IP address of that CAS server. This is a suggestion that Microsoft gives on there site (KB2675690).

Also, make sure that you have setup the file share you are creating the PST file on correctly by following instructions found on the new-mailboxexportrequest instructions.

The FilePath parameter specifies the network share path of the .pst file to which data is exported, for example, \\SERVER01\PST Files\exported.pst.

You need to grant read/write permission to the group Exchange Trusted Subsystem to the network share where you’ll export or import mailboxes. If you don’t grant this permission, you’ll receive an error message stating that Exchange is unable to establish a connection to the target mailbox.

Also, make sure you use the -MRSSever switch so that it is using the CAS server that you modified the Hosts file on.

Then make sure you remove or comment out the entry in the HOSTS file after the new-mailboxexportrequest finishes.