11.3.2. Using Tags in Constraints and Resource Sets

Pacemaker itself only uses tags in constraints. If you supply a tag name instead of a resource name in any constraint, the constraint will apply to all resources listed in that tag.

Example 11.8. Constraint using a tag

<rsc_order id="order1" first="storage" then="all-vms" kind="Mandatory" />

In the example above, assuming the all-vms tag is defined as in the previous example, the constraint will behave the same as:

Example 11.9. Equivalent constraints without tags

<rsc_order id="order1-1" first="storage" then="vm1" kind="Mandatory" />
<rsc_order id="order1-2" first="storage" then="vm2" kind="Mandatory" />
<rsc_order id="order1-3" first="storage" then="vm2" kind="Mandatory" />

A tag may be used directly in the constraint, or indirectly by being listed in a resource set used in the constraint. When used in a resource set, an expanded tag will honor the set’s sequential property.