Starting and stopping cluster services

Starting and stopping cluster services includes these features:

• Start cluster services. When you start the cluster services, PowerHA® SystemMirror® by default automatically activates the resources according to how you defined them, taking into consideration application dependencies, application start and stop scripts, dynamic attributes and other parameters. That is, PowerHA SystemMirror automatically manages (and activates, if needed) resource groups and applications in them.

  You can also start PowerHA SystemMirror with the option to manage resource groups manually. This tells PowerHA SystemMirror not to acquire any resource groups (and applications) automatically for you. During migration from one version of PowerHA SystemMirror to another version you can start and stop cluster services, but you cannot use the manual option when starting cluster services. Manual startup is disabled when migration begins and cannot be used again until the migration is complete.

  You can start PowerHA SystemMirror cluster services on the node(s) without stopping your applications, by selecting an option from SMIT (System Management (C-SPOC) > PowerHA SystemMirror Services > Start Cluster Services).

  PowerHA SystemMirror relies on the application monitor and application startup script to verify whether it needs to start the application for you or whether the application is already running. (PowerHA SystemMirror attempts not to start a second instance of the application.)

• Stopping cluster services. When you stop cluster services, you may select one of the following three actions for the resource groups:
  • Bring resource groups Offline.
  • Move resource groups to other node(s).
  • Unmanage resource groups.

  For more information on resource group states, see the section Resource group behavior during cluster events.