Configuring Failover in Netflow Analyzer

    What is Failover ?

    Failover is an alternative monitoring instance that is used to ensure that your network remains monitored even when your primary monitoring setup goes down. Netflow Analyzer helps in ensuring uninterrupted monitoring of your network by allowing you to configure a secondary monitoring instance on a separate server.

    Failover Architecture

    Working mechanism:

    The primary server updates a value called heartbeat in the database. The heartbeat value is a counter that is incremented by the primary server at a specific frequency of time. The secondary server monitors the heartbeat value to check if it gets updated in the specified time interval. When the primary server goes down, it will not be able to update the heartbeat value in the database. If the heartbeat value in the database is not updated for the last 60 seconds, the primary server is considered to have gone down and the secondary monitoring instance takes over. This secondary server will continue monitoring the network as long as it is up. Meanwhile, the OpManager server that went down, after recovery, will monitor the table for the heartbeat value.

    The information between the primary and secondary instances are synced periodically, thus ensuring that you don't miss critical monitoring data ( such as device status, traps, syslog messages etc., ) when your primary OpManager instance goes down.

    Pre-requisites for setting up Failover server

    Ensure that the following conditions are satisfied:

    • Apply the failover add-on: Apply the Failover - Hot Standby Engine (MSSQL only) add-on in your primary instance. You can purchase the add-on for Netflow Analyzer from here

    • Have the database in a separate server: Ensure that the database for your NetflowAnalyzer installation is setup in a separate server (Not the same server in which primary or secondary OpManager instance is installed).

    • Create a shared folder in a separate server: Some data in Netflow Analyzer are stored in files which are present in the local directory. When failover is configured, instead of a local directory, these files are stored in a shared folder that is accessible by both primary and secondary servers . This ensures that there is no data loss when the secondary server takes over the monitoring process.

    • Create a folder in a separate server and share it with both the primary and secondary servers. Ensure that both primary and secondary servers have access to the shared folder with write permission.
      (Note: The server in which the folder is created should be in the same domain in which your primary and secondary servers are configured. Also, the server in which the folder is created should not be the same server in which the primary or secondary instance is configured.). 

    • Have a virtual IP address: A Virtual IP address is a common IP address that is shared by both primary and secondary server on the same subnet. When the one server goes down, the virtual IP points to the other server.

    • The virtual IP should in IPv4 format and should be static.

    • The primary server's IP, secondary server's IP and the virtual IP should all belong to the same subnet.

    • Both primary and secondary instances are installed in Windows systems.

    • Primary, Secondary and server in which the shared folder is created should all be in the same domain.

    • The primary and secondary servers have the same hardware configurations.

    • The primary server and secondary server must be able to resolve each other's host name and IP address.

    • The Syslogs, SNMP traps and Flows are forwarded to the virtual IP address.

    • Both primary and secondary servers have static IP address.

    • Both primary and secondary OpManager services should have the same port and protocol ( http / https ).

    Both primary and secondary servers have the same time and timezone.

    Activate failover server

    In the Primary server:

    • Stop Netflow Analyzer service
    • Share the <OpManager_Home> folder to the secondary server. Click here to learn how.
    • Open command prompt / terminal with administrator privilege, navigate to <OpManager_Home>\bin and execute the following command: Clone_primary_server.bat
    • Start the OpManager service.

    In the secondary server:

    • Download Configure_failover_server.bat and move it to the desired folder where you wish to have your secondary instance configured.
    • Execute the Configure_failover_server.bat file.
    • Share the <OpManager_Home> folder to the primary server. Click here to learn how.
    • Start the secondary Netflow Analyzer instance.