Recently I’ve had to switch from Backup Exec 2014 to Microsofts System Center Data Protection Manager 2012 R2 to handle our Exchange 2013 CU5 backups due the Backup Exec 2014 not supporting the Exchange 2013 SP1 + Server 2012 R2 feature of clusters without Cluster Administrative Access Points.

This went swimmingly, besides a problem with Exchange 2007 and Exchange 2013 CU5 not being able to be scanned by the 2013 CU5 ESE*.* files, until we attempted to test restores.

At the restore point, I could browse through the trees, but trying to search the recovery points for specific Exchange mailboxes failed.  Totally failed.  No response whatsoever failed.  Pulled out NetMon and looked at traffic and didn’t see the query going to the SQL server failed.

A brief call to Premier support later, and a gentleman quickly gave me the solution as he’d seen it once before:

By default, a limit of 100 connections to the SQL database is allowed, and this needed to be increased in our case.

To do so, in RegEdit, go to HKLM\SOFTWARE\Microsoft\Microsoft Data Protection Manager\DB, and append the following string:

;Max Pool Size=400

To the following 2 keys:

ConnectionString
GlobalDbConnectionString

You should end up having a connection string like so:

Integrated Security=SSPI;Initial Catalog=DPMDB_DPMServerName;Application Name=MSDPM;server=tcp:ServerIPAddr;Connect Timeout=90;Max Pool Size=400

After doing so, close any DPM Administrator Consoles you may have open, then restart the MSDPM and DPMAMService services, reopen the administrator console, and try your search again.