If a Virtual Service goes up and down every 5 minutes for an hour then an email notification is generated for a flapping issue. This is reported as a Virtual Service unavailable issue on the Incidents center page.

To try to resolve this issue, follow the steps below:

  • Check the LoadMaster logs to find out why the health check is failing. It is possible there is a duplicate IP address.
  • Check the LoadMaster health check configuration:
    • Ensure that the health check is configured appropriately.
    • You might need to modify the health check interval. To eliminate this as a possible issue, change the health check settings in the LoadMaster User Interface (UI) in Rules & Checking > Check Parameters > Service Check Parameters:
      • Check Interval (sec): The time (in seconds) between health checks.
      • Connect Timeout (sec): The time (in seconds) before the LoadMaster abandons a health check.
      • Retry Count: The number of health checks that must fail before a LoadMaster marks a server as down. For further information on these parameters, refer to the following section of the Web User Interface (WUI) Configuration Guide: Service (Health) Check Parameters.
    • Review the LoadMaster system logs for any relevant logs relating to the Virtual Service:
      1. In the LoadMaster UI, go to System Configuration > Logging Options > System Log Files.
      2. Click View on the System Message File and Warning Message File.
      3. Search for the IP address of the failing server.
  • Inspect the backend server health:
    • Ensure that the backend servers associated with the Virtual Services are operational and reachable.
    • Review the backend server logs for any indicators of issues or errors.
    • Ensure that the network connectivity between the LoadMaster and backend server is stable.