Exchange Server 2013 two node DAG Unable to mount database after one of the active node crashes

After introduction of Exchange Database Availability Group feature in Exchange 2010 Microsoft has eliminated the FC/ISCSI shared storage requirement to build Exchange high availability.

DAG required cluster Qourom should be configured as File Share Witness to avoid the split brain syndrome circumstances, however we have seen lots of time the unexpected failure of Exchange DAG node couldn’t initiate the automatic fail over of DAG database’s. Following is a quick example and resolution to overcome.

Issue: Mount-Database -Identity MDB2 -Force

Failed to mount database “MDB2”. Error: An Active Manager operation failed. Error: The database action failed. Error:
An error occurred while trying to validate the specified database copy for possible activation. Error:
 MBX1:
Server MBX1.domain.com’ is not up according to the Windows Failover Cluster service.
[Database: MDB2, Server: mbx2.domain.com]
+ CategoryInfo          : InvalidOperation: (MDB2:ADObjectId) [Mount-Database], InvalidOperationException   + FullyQualifiedErrorId : [Server=MBX2,RequestId=aee52336-d23a-4f33-8698-35c697813c16,TimeStamp=1/20/2018 3  :38:04 PM] [FailureCategory=Cmdlet-InvalidOperationException] FEFABAA4, Microsoft. Exchange.  Management. SystemConfiguration tasks.MountDatabase
+ PSComputerName        : MBX2.domain.com

Resolution: Run the following command from Exchange Shell with Administrative permission.

Move-ActiveMailboxDatabase MDB2 -ActivateOnServer MBX2 -SkipHealthChecks -SkipActiveCopyChecks -SkipClientExperienceChecks -SkipLagChecks -MountDialOverride:BESTEFFORT

Confirm

Moving mailbox database “MDB2” from server “PDHHFEXCH01.PDHHF.ae” to server “PDHHFEXCH02.PDHHF.ae”.

Y] Yes  [A] Yes to All  [N] No  [L] No to All  [?] Help (default is “Y”): y

 

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