Issue : On Exchange 2010 DAG database are not mounting
Couldn't mount the database that you specified. Specified database: DB1; Error code: An Active Manager operation failed with a transient error. Please retry the operation. Error: A transient error occurred during discovery of the database availability group topology. Error: Database action failed with transient error. Error: A transient error occurred during a database operation. Error: MapiExceptionJetErrorOutOfMemory: Unable to mount database.
In Hyper-V, Shutdown the Exchange VM to reset the Memory to multiple of 1024.
I reset the memory to 4096 MB and start the Exchange VM.
Now able to mount the Database.