In this cluster type nodes do not share the same physical storage; instead, the passive node continuously replicates database updates, but not the OAB files. Therefore, as the OAB Generation process needs access to the results of previous generation, only one CCR cluster node is able to generate the OAB data files, making such cluster basically asymmetric with regard to OABGen.
To control this behavior the Exchange setup process creates the registry value 'SYSTEM\CurrentControlSet\Services\MSExchangeSA\Parameters\OABGen-Server\EnableOabGenOnThisNode' which contains name of the node installed first, and from now on assumed as ‘primary’ cluster node. Whenever cluster has failed over to the ‘secondary’ node, the scheduled or forced OAB Generation task will log the event id 9395 and finishes.
Event Type: Error
Event Source: MSExchangeSA
Event Category: OAL Generator
Event ID: 9395
OALGen is running on CCR cluster node which does not have registry value 'SYSTEM\CurrentControlSet\Services\MSExchangeSA\Parameters\OABGen-Server\EnableOabGenOnThisNode' or it is not set to this node name. OAB generation will not be performed.
How To Fix
This is an expected error if the ‘primary’ CCR node is temporarily unavailable, so just make sure it is back online . Otherwise, the following registry key needs to be in place and contain valid cluster node name: HKLM\System\CurrentControlSet\Services\MSExchangeSA\Parameters\Server-Name\EnableOabGenOnThisNode ="ThisNodeName".
NOTE: Make sure that you updated the registry value on the CCR node to be the name of the CCR node.