This Knowledgebase article describes the procedure used to perform installation verification testing of a Neverfail Continuity Engine pair. Please see Neverfail Continuity Engine v9.0 Installation Guide for installation verification testing of a Neverfail Continuity Engine trio.
Important: The following procedure provides information about performing Installation Verification testing on a Neverfail Continuity Engine pair to ensure proper installation and configuration.
Additionally, this procedure provides step-by-step procedures to perform a controlled switchover in the event of an application failure and failover in the event of network or hardware failure resulting in excessive missed heartbeats.
Note: In this document, the term “Pair” refers to a Neverfail Continuity Engine pair.
Neverfail Continuity Engine monitors Neverfail services and the system environment to ensure that protected services are available for end users. To monitor services and the system environment, Neverfail Continuity Engine uses plug-ins which are designed for Neverfail services and the system.
If a protected service or the system begins to operate outside of preconfigured thresholds, Neverfail Continuity Engine can automatically switch to make the passive server the active server in the pair that provides services for end users.
Important: These exercises are examples and should be performed in order. Neverfail recommends against attempting to test failover on a properly operating pair by methods such as unplugging a power cord. At the moment power is lost, any data not written to the passive server is lost. Neverfail recommends that all actions intended to verify operation of the passive server be performed as a switchover rather than a failover.
Prior to initiating the Installation Verification process in a pair, Neverfail Continuity Engine must be configured with the Primary server as active and the Secondary server as passive. Additionally, the following prerequisites must be met:
- The Secondary server must be synchronized with the Primary server.
- All protected services must be operating normally.
- If installed in a LAN environment, using the Neverfail Advanced Management Client, verify that Failover from Primary server to Secondary server if channel heartbeat is lost for failover timeout is selected from the Server: Monitoring > Configure Failover dialog (default setting).
- If installed in a WAN environment, using the Neverfail Advanced Management Client, you must manually select Failover from Primary server to Secondary server if channel heartbeat is lost for failover timeout in the Server: Monitoring > Configure Failover dialog.
Important: Prior to starting the Installation Verification process, ensure that a known good backup of the Primary server exists and examine the Windows event logs for recent critical errors.
Neverfail provides an executable, nfavt.exe, to emulate conditions that result in auto-switchover so you can verify that your Neverfail Continuity Engine installation performs as expected. This section guides you through the steps necessary to perform this verification.
Steps to Perform
Important: If you encounter errors and or find it necessary to back out the changes made by this exercise, you can stop at any point and perform the steps described in the Back-out Procedure (Auto-switchover) to return the Pair to its original operating configuration and state.
Table 2: Perform the following procedure to verify Auto-Switchover in a Pair configuration.
Open a command prompt.
Change directory to C:\Program Files\Neverfail\R2\Bin
Execute nfavt.exe When prompted, “Are you sure you wish to continue”, click Continue.
Service is switched to the Secondary server and Neverfail Engine shuts down on the Primary.
Login to the Engine Management Service
In the Status pane of the Engine Management Service, review the status of the server pair.
The Status pane indicates that the Secondary server is active.
Verify all protected applications have started on the Secondary.
Services are running on the Secondary.
Verify data is present.
Data is present.
Successful completion of this procedure leaves the Neverfail Engine pair in the state necessary to perform the second part of the Installation Verification process, detailed in Exercise 2 - Data Verification.
If for any reason you find it necessary to back out of this exercise, you can stop at any point and return the pair to the state it was in at the beginning of this exercise by performing the following steps:
- Shut down Neverfail Engine and protected services on all servers.
- Complete the following on both servers:
- Open the Configure Server wizard.
- Select the Machine tab.
- Select the Primary server as active.
- Click Finish.
- On the Secondary server, right-click the taskbar icon and select Start Neverfail Engine.
- Verify that the Secondary server is passive (S/–).
- On the Primary server, right-click the taskbar icon and select Start Neverfail Engine.
- After Neverfail Engine starts, login to the Engine Management Service.
- Verify that applications have started and replication to the passive server has resumed.
The Data Verification exercise validates that data is synchronized between the servers resulting in current data on the active server following the Auto-switchover exercise performed previously. The objective is to take a working active server (the Secondary server) and synchronize it with the passive (Primary server). This exercise also demonstrates that all the correct services stopped when the Primary server became passive.
Neverfail Continuity Engine is running on the Secondary active server. Login to the Secondary server and using the System Tray icon, verify that the server status displays S/A. Neverfail Continuity Engine is not running on the Primary server which is set to passive. Login to the Primary server and using the System Tray icon, verify that the server status displays -/- to indicate that Neverfail Continuity Engine is not running.
Steps to Perform
Table 3: Perform the following steps to verify that data is synchronized following Auto-switchover in a Pair configuration.
On the Primary server, right-click the taskbar icon and select Start Neverfail Engine.
Neverfail Engine successfully starts.
Login to the Engine Management Service.
In the Protected Servers pane of the Engine Management Service, select the server pair.
The Summary screen is displayed.
Review the Status pane and verify the connection from the Secondary (active) to Primary (passive).
The Status pane shows a connection from the Secondary server to the Primary server.
View the System Summary pane and wait for both the File System and the Registry status to display as Synchronized. Access the Neverfail Engine logs and confirm that no exception errors occurred during the synchronization process.
Data replication resumes from the Secondary server back to the Primary server. Both the File System & Registry status become Synchronized.
Successful completion of this procedure leaves the Neverfail Continuity Engine Pair in the state necessary to perform the final part of the Installation Verification process, detailed in Exercise 3 - Switchover.
The Switchover exercise demonstrates the ability to switch the functionality and operations of the active server on command to the other server in the pair using the Neverfail Continuity Engine. Perform this exercise only after successfully completing the Auto-switchover and Data Verification Exercises.
Neverfail Continuity Engine is running on the Secondary active server and Primary passive server. Using the Engine Management Service Summary page, verify that the Secondary server is active and that the Primary server is passive.
Steps to Perform
Table 4: Perform the following steps to switch functionality and operations on command fromthe active server to the ready-standby server.
Using the Engine Management Service, review the Summary pane to verify that both the File System and Registry status are Synchronized.
Navigate to the Actions drop-down and click on Make Primary Server Active.
The Engine Management Service Summary Status pane displays the applications stopping on the active server. Once all applications are stopped, the active server becomes passive and the passive server becomes active. The Summary Status pane shows the applications starting on the newly active server. Both the File System and Registry status are Synchronized.
Confirm application performance and availability meets previously defined criteria. Verify that client applications are running as expected after the switchover process.
Services continue to be provided as before the switchover occurred. You may need to refresh or restart some client applications as a result of a switchover.
Successful completion of this procedure indicates a successful outcome from the Installation Verification process.
Neverfail Continuity Engine v8.0 and Later