Controlling a HA Service

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2021-03-30 13:05

When a new HA service is added to a cluster, its state will initially be set to "stopped" and "automatic". The cluster will then start the service on its preferred node.

After the service is started for the first time, its state can be controlled simply using the supplied webapp or command line utilities.

The steps that follw make the following assumptions:

  • A cluster has already been created on a set of nodes. For more information about creating a cluster, see Cluster Creation
  • An HA service has already been created in the cluster. For more information about creating a ZFS HA service, see Service Creation

For more information about HA service status, see Understanding a service status.

Controlling a Service from the Browser

All configured HA services in the cluster can be controlled from the "Cluster Control" tab.

Upon navigating to "Cluster Control" a summary of each service's state will be shown for all cluster nodes:

In this example, it can be easily seen that there is a single service "lio-pool" which is running on the node CentOS8-1, automatic on both nodes and also unblocked on both nodes.

Setting a Service Mode

A service's mode can be set to either "automatic" or "manual" from this tab. Click the "Actions" button for the service instance that is to be controlled. The display will change to show available actions:

One of the options shown is to set the service mode. If the service is in automatic mode as in the example, then the option will be to set the service to manual. If it is already manual, then there will be the option to set it to automatic mode.

Select the option to change the service's mode, confirm the action and the service status will change:

Moving a Service

A running service can be moved easily from the Cluster Control tab. It is not necessary to change the service mode (automatic/manual) on either the source or destination node - any changes to these settings are handled internally by RSF-1.

The service can only move if it is running on the source node and stopped on the destination. Any other states will block the move operation.

Select the action to move the service from the running node to a remote node:

A confirmation window will be shown with an option to retain failover modes after the service move. This option controls whether the service mode settings move with the service.

When the service move is confirmed, the state changes will be displayed in real-time in the Cluster Control view:

Starting a Service

It is only possible to start a service when it is stopped on all nodes in the cluster. This will be shown in the list of actions:

Select the option to start the service on one of the cluster nodes and the service state changes will be shown in the Cluster Control view:

Stopping a Service

To stop a service, select the appropriate option from the list of actions for the node that is currently running the service.

When a service is stopped on a node, the service move is set to manual on that node to avoid the service starting again.

Note that if it is not desired for the service to start on another node after the service stop completes, it is important to set the service to manual mode on all nodes before performing the stop action.

When the stop completes, the service will be shown as manual and stopped on all nodes:

Controlling a Service using the Command Line

Setting a Service Mode

 

Moving a Service

 

Starting a Service

 

Stopping a Service

 

Repairing a Broken Service

 

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