10.2.11. Determining Which Instance is Promoted

⁠10.2.11. Determining Which Instance is Promoted

Pacemaker can choose a promotable clone instance to be promoted in one of two ways:

Promotion scores: These are node attributes set via the crm_master utility, which generally would be called by the resource agent’s start action if it supports promotable clones. This tool automatically detects both the resource and host, and should be used to set a preference for being promoted. Based on this, promoted-max, and promoted-node-max, the instance(s) with the highest preference will be promoted.
Constraints: Location constraints can indicate which nodes are most preferred as masters.

Example 10.11. Explicitly preferring node1 to be promoted to master

<rsc_location id="master-location" rsc="myMasterRsc">
    <rule id="master-rule" score="100" role="Master">
      <expression id="master-exp" attribute="#uname" operation="eq" value="node1"/>
    </rule>
</rsc_location>