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10.2.2. Promotable clones

If a clone is promotable, its instances can perform a special role that Pacemaker will manage via the promote and demote actions of the resource agent.
Services that support such a special role have various terms for the special role and the default role: primary and secondary, master and replica, controller and worker, etc. Pacemaker uses the terms master and slave, [16] but is agnostic to what the service calls them or what they do.
All that Pacemaker cares about is that an instance comes up in the default role when started, and the resource agent supports the promote and demote actions to manage entering and exiting the special role.

[16] These are historical terms that will eventually be replaced, but the extensive use of them and the need for backward compatibility makes it a long process. You may see examples using a master tag instead of a clone tag with the promotable meta-attribute set to true; the master tag is supported, but deprecated, and will be removed in a future version. You may also see such services referred to as multi-state or stateful; these means the same thing as promotable.