Configuring the Distribution of Resource Group Load Across Nodes

You can enable the automatic distribution of resource group load across nodes by setting load limits. You assign load factors to resource groups, and the load factors correspond to the defined load limits of the nodes.

The default behavior is to distribute resource group load evenly across all the available nodes. Each resource group is started on a node from its node list. The Resource Group Manager (RGM) chooses a node that best satisfies the configured load distribution policy. As resource groups are assigned to nodes by the RGM, the resource groups' load factors on each node are summed up to provide a total load. The total load is then compared against that node's load limits.

You can configure load limits in a global cluster or a zone cluster.

The factors you set to control load distribution on each node include load limits, resource group priority, and preemption mode. In the global cluster, you can set the Concentrate_load property to choose the preferred load distribution policy: to concentrate resource group load onto as few nodes as possible without exceeding load limits or to spread the load out as evenly as possible across all available nodes. The default behavior is to spread out the resource group load. Each resource group is still limited to running only on nodes in its node list, regardless of load factor and load limit settings.

Note - You can use the command line or the clsetup utility to configure load distribution for resource groups. The following procedure illustrates how to configure load distribution for resource groups using the clsetup utility. For instructions on using the command line to perform these procedures, see Configuring Load Limits in Oracle Solaris Cluster System Administration Guide.

This section contains the following procedures:

How to Configure Load Limits for a Node
How to Set Priority for a Resource Group
How to Set Load Factors for a Resource Group
How to Set Preemption Mode for a Resource Group
How to Concentrate Load Onto Fewer Nodes in the Cluster

How to Configure Load Limits for a Node

Each cluster node can have its own set of load limits. You assign load factors to resource groups, and the load factors correspond to the defined load limits of the nodes. You can set soft load limits (which can be exceeded) or hard load limits (which cannot be exceeded).

Assume the root role on one active node of the cluster.
Start the clsetup utility.
```
phys-schost# clsetup
```
The clsetup menu is displayed.
Choose the menu item, Other Cluster Tasks.
The Other Cluster Tasks Menu is displayed.
Choose the menu item, Manage Resource Group Load Distribution.
The Manage Resource Group Load Distribution Menu is displayed.
Choose the menu item, Manage Load Limits.
The Manage load limits Menu is displayed.
Type yes and press the Return key to continue.
Type the option number for the operation you want to perform and press the Return key.
You can create a load limit, modify a load limit, or delete a load limit.
If you chose to create a load limit, select the option number for the node where you want to set the load limit.
If you want to set a load limit on a second node, select the option number for the second node and press the Return key. After you have selected all the nodes where you want to configure load limits, type q and press the Return key.
Type yes and press the Return key to confirm the nodes you selected in Step 8.
Type the name of the load limit and press the Return key.
For example, type mem_load as the name of a load limit.
Type yes or no to specify a soft limit value and press the Return key.
If you typed yes, type the soft limit value and press Enter.
Type yes or no to specify a hard limit value and press the Return key.
If you typed yes, type the hard limit value and press Enter.
Type yes and press the Return key to proceed with creating the load limit.
Type yes to proceed with the update and press the Return key.
The message Command completed successfully is displayed, along with the soft and hard load limits for the nodes you selected. Press the Return key to continue.
You can modify or delete a load limit by following the prompts in the clsetup utility.
Return to the previous menu by typing q and pressing the Return key.

How to Set Priority for a Resource Group

You can configure a resource group to have a higher priority so that it is less likely to be displaced from a specific node. If load limits are exceeded, lower-priority resource groups might be forced offline.

Assume the root role on one active node of the cluster.
Start the clsetup utility.
```
phys-schost# clsetup
```
The clsetup menu is displayed.
Choose the menu item, Other Cluster Tasks.
The Other Cluster Tasks Menu is displayed.
Choose the menu item, Manage Resource Group Load Distribution.
The Manage Resource Group Load Distribution Menu is displayed.
Choose the menu item, Set Priority Per Resource Group.
The Set the Priority of a Resource Group Menu is displayed.
Type yes and Press the Return key.
Type the option for the resource group and press the Return key.
The existing Priority value is displayed. The default Priority value is 500.
Type the new Priority value and press the Return key.
Type yes to confirm your entry and press the Return key.
Press the Return key to return to the previous menu.
The Manage Resource Group Load Distribution Menu is displayed.

How to Set Load Factors for a Resource Group

A load factor is a value that you assign to the load on a load limit. Load factors are assigned to a resource group, and those load factors correspond to the defined load limits of the nodes.

Assume the root role on one active node of the cluster.
Start the clsetup utility.
```
phys-schost# clsetup
```
The clsetup menu is displayed.
Choose the menu item, Other Cluster Tasks.
The Other Cluster Tasks Menu is displayed.
Choose the menu item, Manage Resource Group Load Distribution.
The Manage Resource Group Load Distribution Menu is displayed.
Choose the menu item, Set Load Factors Per Resource Group.
The Set the load factors of a Resource Group Menu is displayed.
Type yes and press the Return key.
Type the option number for the resource group and press the Return key.
Type the desired load factor.
For example, you can set a load factor called mem_load on the resource group you selected by typing mem_load@50. Press Ctrl-D when you are done.
Press the Return key to proceed with the update.
Press the Return key to return to the previous menu.
The Manage Resource Group Load Distribution Menu is displayed.

How to Set Preemption Mode for a Resource Group

The preemption_mode property determines if a resource group will be preempted from a node by a higher-priority resource group because of node overload. The property indicates the cost of moving a resource group from one node to another.

Assume the root role on one active node of the cluster.
Start the clsetup utility.
```
phys-schost# clsetup
```
The clsetup menu is displayed.
Choose the menu item, Other Cluster Tasks.
The Other Cluster Tasks Menu is displayed.
Choose the menu item, Manage Resource Group Load Distribution.
The Manage Resource Group Load Distribution Menu is displayed.
Choose the menu item, Set Preemption Mode per Resource Group.
The Set the Preemption Mode of a Resource Group Menu is displayed.
Type yes and press the Return key to continue.
Type the option number for the resource group and press the Return key.
If the resource group has a preemption mode set, it is displayed, similar to the following:
```
The preemption mode property of "rg11" is currently set to the following: preemption mode:  Has_Cost
```
Type the option number for the preemption mode you want and press the Return key.
The three choices are Has_cost, No_cost, or Never.
Type yes to proceed with the update and press the Return key.
Press the Return key to return to the previous menu.
The Manage Resource Group Load Distribution Menu is displayed.

How to Concentrate Load Onto Fewer Nodes in the Cluster

Setting the Concentrate_load property to false causes the cluster to spread resource group loads evenly across all available nodes in the resource groups' node lists. By default, the Concentrate_load property is set to FALSE.

If you set this property to TRUE, the cluster attempts to concentrate resource group load on the fewest possible nodes without exceeding any configured hard or soft load limits.

Note - When specifying Concentrate_load=TRUE, if a resource group RG2 declares a ++ or +++ affinity for a resource group RG1, avoid setting any nonzero load factors for RG2. Instead, set larger load factors for RG1 to account for the additional load that would be imposed by RG2 coming online on the same node as RG1. This will allow the Concentrate_load feature to work as intended. Alternately, you can set load factors on RG2 but avoid setting any hard load limits for those load factors—set only soft limits. This will allow RG2 to come online even if the soft load limit is exceeded.

You can only set the Concentrate_load property in a global cluster; you cannot set this property in a zone cluster. In a zone cluster, the default setting is always FALSE.

Assume the root role on one active node of the cluster.
Start the clsetup utility.
```
phys-schost# clsetup
```
The clsetup menu is displayed.
Choose the menu item, Other cluster tasks.
The Other Cluster Tasks Menu is displayed.
Choose the menu item, Set the concentrate_load Property of the Cluster.
The Set the Concentrate Load Property of the Cluster Menu is displayed.
Type yes and press the Return key.
The current value of TRUE or FALSE is displayed.
Type yes to change the value and press the Return key.
Type yes to proceed with the update and press the Return key.
Press the Return key to return to the previous menu.
The Other Cluster Tasks Menu is displayed.

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