Resolve Two Passive Servers (Pair) or Three Passive Servers (Trio)

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Summary

This Knowledgebase article provides information about the occurrence of all servers passive including the symptoms, causes, and resolutions.


More Information

All servers are passive at the same time

Symptoms

The first indication that Neverfail may be experiencing all servers are passive is when users are unable to connect to protected applications. This situation can prove serious to your business, and should be addressed immediately. If you have already configured alerts, you will receive notification that replication is not functioning properly.

Cause

  • All passive being servers is generally the result of some type of sudden failure on the active server - for example, unexpected termination of the Neverfail Server R2 service, a transient power failure, a server reset triggered from the Power or Reset button, or any other type of unclean shutdown. Following an unclean shutdown, an active server will automatically assume the passive role in order to isolate itself from the network until the failure can be investigated.
  • The active server suffers a failure before completion of the 'handshake' which establishes the Neverfail Channel. In this situation, the passive server has no way of detecting that the active server is not responding when the failure occurs - no channel connection was established, so it is impossible for the passive server to determine the condition of the active server. The active server may suffer a transient failure as described above and the passive server cannot respond by failing over into the active role. This leaves both servers in the passive role.
  • All servers experience a power outage simultaneously (for example, because they are using the same power source and none are attached to a UPS). In this situation, a failover will not be possible. When the servers are rebooted, each will display the error message:

'Cannot start replication because previous run did not shutdown properly. Check configuration'.

Note: If the user attempts to start Neverfail Heartbeat without reconfiguring one server in the group as active, Heartbeat will respond with the warning:

'[U16] Serious configuration mismatch between the two servers. Please reconfigure so there is one and only one Primary, and one and only one Active.'

Resolution

To resolve all server being passive, follow the steps below:

  1. Determine which server should be active.
  2. If Neverfail Heartbeat is running on any server, shut it down. Leave any protected applications running on the server you have chosen to make active.
  3. On the server you have chosen to make active:
    1. Open the Configure Server wizard and select the Machine tab.

      Note: Do NOT change the Identity (Primary / Secondary/Tertiary).

      • For Neverfail versions 5.5.[n] and earlier: set the server role to Active .
      • For Neverfail versions 6.0.[n] and later: set the Active server to point to the identity of the local server.
    2. Click Finish .
  4. On the server(s) you have chosen to make passive:
    1. Open the Configure Server wizard and select the Machine tab.

      Note: Do NOT change the Identity (Primary / Secondary/Tertiary).

      • For Neverfail versions 5.5.[n] and earlier: set the server role to Passive .
      • For Neverfail versions 6.0.[n] and later: set the Active server to point to the identity of the server that should be the active server in the Cluster.
        For example, if the desired active server (identified at step 1) is the Primary server, the Active Server radio button should be set on Primary regardless if the Physical Hardware Identity is Primary , Secondary or Tertiary .
    2. Click Finish and exit the wizard.
  5. Reboot all servers. This ensures that all protected application services are stopped on the passive servers and started on the active server.
  6. Start Neverfail Heartbeat on all servers.

Applies To

All Versions


Related Information

Knowledgebase article #516 : Resolve Two Active Servers

KBID-984

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