Introduction

There can be situations when a Controller Cluster should be converted reverted to act as a Standalone Controller:

• In case of an architecture decision to continue with a Standalone Controller.
• In case of severe loss of journal data, for example if journals of both one of the Controller instances and of the Cluster Watch Agent have not been consistently written to disk or are not available after a server crash or file system crash.

Converting Reverting a Controller Cluster to a Standalone Controller offers to re-instate the Cluster at any later point in time, see see JS7 - How to convert a Standalone Controller to a Controller Cluster.

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Reverting the Controller Cluster

Stopping the Controller Cluster

As a prerequisite both active and standby Controller instances have to be terminated.

Reverting the Controller Journal

Users decide which Controller instance should become the Standalone Controller to continue operations.

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# reverting Controller journal for Unix with no running Controller instances
./controller_instance.sh revert

# reverting Controller journal for Unix with a running Controller instance that is stopped and reverted (available starting from release 2.5.1)
./controller_instance.sh stop --revert

@rem reverting Controller journal for Windows with no running Controller instances
./controller_instance.cmd revert

@rem reverting Controller journal for Windows with a running Controller instance that is stopped and reverted (available starting from release 2.5.1) .\controller_instance.cmd stop --revert

Explanation:

• Running the above script will remove any cluster related items from the Controller instance's journal.
• This allows the Controller instance to be started as a Standalone Controller.
• Standalone Controllers
  • do not connect to a Cluster Watch Agent,
  • do not connect nor can be connected to/from a second Controller instance acting in a standby role.

Configuring the Standalone Controller

The Controller's administrative menu is invoked from the JOC Cockpit user interface as follows:

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At the point in time when submitting the changes the Controller will not be started. Therefore the Test Connection button cannot be used.

Starting the Standalone Controller

With the Controller type being modified to Standalone, users can start the Standalone Controller from the command line like this:

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@rem starting the Standalone Controller for Windows from the command line
.\controller_instance.cmd start

@rem starting the Standalone Controller Windows Service from the command line
.\controller_instance.cmd start-service

@rem alternatively the Standalone Controller can be started from the Windows Service Panel

Further Resources

• JS7 - Controller Configuration Items
• JS7 - Controller - Command Line Operation
• JS7 - Agent Command Line Operation
• JS7 - How to convert a Standalone Controller to a Controller Cluster

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