8.2.2. Multi-state Constraints

In most cases, a multi-state resources will have a single copy on each active cluster node. If this is not the case, you can indicate which nodes the cluster should preferentially assign copies to with resource location constraints. These constraints are written no differently than those for regular resources.

For information on resource location constraints, see Section 6.1, “Location Constraints”.

You can create a colocation constraint which specifies whether the resources are master or slave resources. The following command creates a resource colocation constraint.

pcs constraint colocation add [master|slave] source_resource with [master|slave] target_resource [score] [options]

For information on colocation constraints, see Section 6.3, “Colocation of Resources”.

When configuring an ordering constraint that includes multi-state resources, one of the actions that you can specify for the resources is promote, indicating that the resource be promoted from slave to master. Additionally, you can specify an action of demote, indicated that the resource be demoted from master to slave.

The command for configuring an order constraint is as follows.

pcs constraint order [action] resource_id then [action] resource_id [options]

For information on resource order constraints, see Section 6.2, “Order Constraints”.