How to Perform a Managed Failover with Neverfail Continuity Engine

How to Perform a Managed Failover with Neverfail Continuity Engine

Summary

This Knowledgebase article provides information about the automatic switchover process and how to trigger a managed switchover.

 

More Information

A switchover can be triggered, automatically or manually (managed) and can only occur if the system is fully synchronized. Switchovers cannot be performed if either the active or the passive servers are in an unsynchronized or unknown state. The server's synchronization status can be viewed from the Neverfail Advanced Client > Server: Summary page.  The Server Pair's Registry Status AND File System Status must report as synchronized for a switchover to take place.

It is also important to review the queue information before triggering a manual switchover. If the active and passive server queues are large, and file operations on the active server are high, it is recommended that you wait to perform the switchover until the queue clears. The screen will indicate manual or automatic switchover progress.

Procedure

How to Trigger a Managed Switchover

Note: When deployed in a trio, the procedure for a conducting a managed switchover is identical as when deployed in a pair.

A managed switchover may be used to perform maintenance on the Primary Server.

  1. Open the Neverfail Advanced Client. Check the queue information for any signs of large queue operations on the Data: Traffic/Queues page.
  2. If queues are small, select the Secondary server graphic on the Server: Summary page and click the Make Active button. This reverses the role of the servers; the active (Primary) server will now become the passive server and the passive (Secondary) becomes active.
  3. Following maintenance, you can again trigger a switchover by clicking the Make Active button causing the active (Secondary) server to become the passive server, and the passive (Primary) server again to become the active server.

The Switchover Process

An automatic switchover will occur, for example, when a monitored protected application has failed. The Server: Summary page of the Neverfail Advanced Client will indicate the status of this process.

The procedure that is executed during a switchover operation (manual or automatic) includes the following steps:

  1. Protected applications are stopped on the Primary Server. Once the protected applications have been stopped, no more disk updates are generated.
  2. All updates that are still queued on the active server are sent to the passive server. After this step, all updates are available on the passive server.
  3. The status of the active server changes to ‘switching to passive’. The server will now no longer be visible from the network.
  4. All queued updates are applied on the passive server.
  5. The role of the passive server changes to active. After this step the newly active server will start intercepting disk I/O’s and queue them for the new passive server. The new active server will now be visible on the network with the same identity as the old active server.
  6. The old active server status changes from ‘switching to passive’ to passive, the new passive server will now accept updates from the new active server.
  7. Protected applications are started on the new active server. The protected applications will now start generating disk updates.
  8. The switchover has completed.

 

Applies To

Neverfail Continuity Engine

 

Related Information

None

 

KBID-2835


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