6.3. Specifying in which Order Resources Should Start/Stop

The way to specify the order in which resources should start is by creating rsc_order constraints.

Table 6.2. Properties of an Ordering Constraint

Field	Description
`id`	A unique name for the constraint
`first`	The name of a resource that must be started before the `then` resource is allowed to.
`then`	The name of a resource. This resource will start after the `first` resource.
`kind`	How to enforce the constraint. (Since 1.1.2) * Optional - Just a suggestion. Only applies if both resources are starting/stopping. * Mandatory - Always. If first is stopping or cannot be started, then must be stopped. * Serialize - Ensure that no two stop/start actions occur concurrently for a set of resources.
`symmetrical`	If true, which is the default, stop the resources in the reverse order. Default value: true

6.3.1. Mandatory Ordering

When the then resource cannot run without the first resource being active, one should use mandatory constraints. To specify a constraint is mandatory, use scores greater than zero. This will ensure that the then resource will react when the first resource changes state.

If the first resource was running and is stopped, the then resource will also be stopped (if it is running).
If the first resource was not running and cannot be started, the then resource will be stopped (if it is running).
If the first resource is (re)started while the then resource is running, the then resource will be stopped and restarted.