These situation are:

• You may need to colocate a set of resources but the resources do not necessarily need to start in order.
• You may have a resource C that must be colocated with either resource A or B, but there is no relationship between A and B.
• You may have resources C and D that must be colocated with both resources A and B, but there is no relationship between A and B or between C and D.

In these situations, you can create a colocation constraint on a set or sets of resources with the pcs constraint colocation set command.

You can set the following options for a set of resources with the pcs constraint colocation set command.

• sequential, which can be set to true or false to indicate whether the members of the set must be colocated with each other.

  Setting sequential to false allows the members of this set to be colocated with another set listed later in the constraint, regardless of which members of this set are active. Therefore, this option makes sense only if another set is listed after this one in the constraint; otherwise, the constraint has no effect.

• role, which can be set to Stopped, Started, Promoted, or Unpromoted.

You can set the following constraint option for a set of resources following the setoptions parameter of the pcs constraint colocation set command.

• id, to provide a name for the constraint you are defining.
• score, to indicate the degree of preference for this constraint. For information about this option, see the "Location Constraint Options" table in Configuring Location Constraints

When listing members of a set, each member is colocated with the one before it. For example, "set A B" means "B is colocated with A". However, when listing multiple sets, each set is colocated with the one after it. For example, "set C D sequential=false set A B" means "set C D (where C and D have no relation between each other) is colocated with set A B (where B is colocated with A)".

The following command creates a colocation constraint on a set or sets of resources:

# pcs constraint colocation set resource1resource2] [resourceN]... [options] [set resourceXresourceY] ... [options]] [setoptions [constraint_options]]

Use the following command to remove colocation constraints with source_resource:

# pcs constraint colocation remove source_resourcetarget_resource