Settling time, dynamic node priority, and fallback timer

You can configure some additional parameters for resource groups that dictate how the resource group behaves at startup, fallover, and fallback.

The following are additional parameters for resource groups that you can configure:

Settling Time

You can configure a startup behavior of a resource group by specifying the settling time for a resource group that is currently offline. When the settling time is not configured, the resource group starts on the first available higher priority node that joins the cluster. If the settling time is configured, PowerHA® SystemMirror® waits for the duration of the settling time period for a higher priority node to join the cluster before it activates a resource group. Specifying the settling time enables a resource group to be acquired on a node that has a higher priority, when multiple nodes are joining simultaneously. The settling time is a cluster-wide attribute that, if configured, affects the startup behavior of all resource groups in the cluster for which you selected Online on First Available Node startup behavior.

Distribution Policy

You can configure the startup behavior of a resource group to use the node-based distribution policy. This policy ensures that during startup, a node acquires only one resource group. See the following section for more information.

Dynamic Node Priority

You can configure a fallover behavior of a resource group to use one of three dynamic node priority policies. These policies are based on RSCT variables such as the most free memory or lowest use of CPU. To recover the resource group PowerHA SystemMirror selects the node that best fits the policy at the time of fallover.

Note: Fallover that uses the Dynamic Node Priority option is not supported when sites are configured.

Delayed Fallback Timer

You can configure a fallback behavior of a resource group to occur at one of the predefined recurring times: daily, weekly, monthly and yearly, or on a specific date and time, by specifying and assigning a delayed fallback timer. This is useful, for instance, for scheduling the resource group fallbacks to occur during off-peak business hours.