Oracle Enterprise Manager (OEM) 13c is capable of monitoring virtual guest hosts running on Exalogic (virtual configuration). OEM will connect (read-only) to the Oracle VM Manager and get the configuration and status of the VM’s running there. Then you can deploy an agent to those VM hosts and you have a complete monitoring solution for Exalogic.
The problem comes when for whatever reason you have to drop those VM’s from Exalogic but you want to keep the OEM configuration in place. For example, you want to drop the VM from Exalogic and then restore it from backup.
In this case you want to keep your monitoring configuration (metrics, credentials, etc.), but you realize that the agent was removed (along with all targets) as soon as you drop the VM from Exalogic.
This setup is being driven by metric like configuration. This synchronization is happening every minute by default. This is covered on below Oracle’s document:
The solution was to set this synchronization schedule from every 1 minute to every 1 day.