Sunday, September 16, 2007

Cluster, Resource, and Resource Group

Affect the Group setting of a resource




As shown, the Restart is selected. If the resource fails, the Cluster service attempts to restart it and all its dependent resources. If the resouce fails again, the Cluster service attempts to restart it again. Because the Affect the Group is selected, which has the Threshold:3 and period:900 seconds, if within 900 seconds the resource fails 3 times, the resouce is brought offline. It causes the Resouce Group failure. The resource group will be moved to the other node, which has the ownership of the resource group. The Cluster Service on that node will bring all the resource online.

Again, if a resource in that group fails 3 times within 900 seconds, it causes the whole resource group to be moved to the other node. This back and forth cannot be forever. The screenshot below shows the settings.

The Default Failover setting of a Resouce Group has Threshold:10 and period:6 hours. Within 6 hours, if a resouce group fails over 10 times back and forth, the whole resouce group is brought offline--failed state.