Core Issue
If the Subscriber server is taken off the network for maintenance when the server crashes, the services can be affected by this. The Database Layer Monitor is one such service. If this service is down, users are unable to CallForward and receive business calls.
Restart the Database Layer Monitor service on the Publisher in the cluster in order to recover the issue. This is not service impacting.
Resolution
If the Database Layer Monitor service does not start, aupair.exe can be killed from the Task Manager or any third-party tool. Once it is killed, the Database Layer Monitor service starts fine.
For more information about the service crash, refer to How to Identify a Cisco CallManager Restart as a Crash or Service Shutdown.
Also, any issues related to the hard drives on the server (for example, bad sectors) causes the service crash. To resolve this, use the appropriate hardware.
In case the Subscriber server needs to be rebuilt, it must be done using the proper CDs only. Installation of the servers using the ghost image can lead to other issues and an unsupported environment for Cisco TAC.
