This Knowledge Base article talks about an issue where attempting to protect a SQL Server AlwaysOn AG using DPM 2012 fails with error 0x80990F75:
  
When attempting to protect a SQL Server AlwaysOn Availability Group (AG) using System Center 2012 Data Protection Manager (DPM), the job fails with the following error:
The DPM job failed for SQL Server 2012 database < DBname > on < serverName> because the SQL Server instance refused a connection to the protection agent. (ID 30172 Details: Internal error code: 0x80990F75)
In SQL, AlwaysOn is configured as follows:
   Availability Mode: Synchronous Commit
   
   Failover Mode: Automatic
   
   Connections in Primary Role: Allow all connections
   
   
    Readable Secondary: No
   
  
   Backup Preferences:
   
   Perfer Secondary
   
   Priority: 50 (for each node)
   
   Exclude Replica: False (for each node)
  
In general: Prefer Secondary - Backups should occur on a secondary replica except when the primary replica is the only replica online. If there are multiple secondary replicas available then the node with the highest backup priority will be selected for backup. In the case that only primary replica is available then backup should occur on the primary replica.
CauseThis occurs due to incorrect SQL AlwaysOn settings for DPM backups where Make Readable Secondary is set to No .
ResolutionSet Make Readable Secondary to Yes on all the nodes.
More InformationIf setting Make Readable Secondary to Yes on all the nodes does not resolve the issue, verify on the SQL server that the DPMRA service is running under the Local System account AND that the NT Authority\System has the sysadmin selected for the server role in SQL studio.
   Steps
   
   ****
   
   a.) On the SQL side the DPMRA service should run under Local system. You can verify this via services in computer management.
  
   b.) Connect to the
   
    SQL 2012 instance
   
   with the help of SQL2012 Management Studio > select and expand
   
    Security
   
   > select and expand
   
    Logins
   
   > right click on the
   
    NT AUTHORITY\SYSTEM
   
   and select
   
    Properties
   
   > click on
   
    Serverroles
   
   > check the
   
    sysadmin
   
   checkbox
   
    >
   
   click
   
    OK
    
   
   after this, In certain cases it may also be necessary to reinstall the DPM Agent on the SQL server
   
    OR
   
   manually run the
   
    SetDPMServer
   
   command on the SQL server specifying the DPM server.
  
For the most current version of this article please see the following:
J.C. Hornbeck | Knowledge Engineer | Management and Security Division
Get the latest System Center news on Facebook and Twitter :
   
   
  
   App-V Team blog:
   
    http://blogs.technet.com/appv/
   
   
   ConfigMgr Support Team blog:
   
    http://blogs.technet.com/configurationmgr/
   
   
   DPM Team blog:
   
    http://blogs.technet.com/dpm/
   
   
   MED-V Team blog:
   
    http://blogs.technet.com/medv/
   
   
   Orchestrator Support Team blog:
   
    http://blogs.technet.com/b/orchestrator/
   
   
   Operations Manager Team blog:
   
    http://blogs.technet.com/momteam/
   
   
   SCVMM Team blog:
   
    http://blogs.technet.com/scvmm
   
   
   Server App-V Team blog:
   
    http://blogs.technet.com/b/serverappv
   
   
   Service Manager Team blog:
   
    http://blogs.technet.com/b/servicemanager
   
   
   System Center Essentials Team blog:
   
    http://blogs.technet.com/b/systemcenteressentials
   
   
   WSUS Support Team blog:
   
    http://blogs.technet.com/sus/
   
  
   The Forefront Server Protection blog:
   
    http://blogs.technet.com/b/fss/
   
   
   The Forefront Endpoint Security blog :
   
    http://blogs.technet.com/b/clientsecurity/
   
   
   The Forefront Identity Manager blog :
   
    http://blogs.msdn.com/b/ms-identity-support/
   
   
   The Forefront TMG blog:
   
    http://blogs.technet.com/b/isablog/
   
   
   The Forefront UAG blog:
   
    http://blogs.technet.com/b/edgeaccessblog/