Product SiteDocumentation Site

13.5. Advanced Fencing Configurations

Some people consider that having one fencing device is a single point of failure [16], others prefer removing the node from the storage and network instead of turning it off.
Whatever the reason, Pacemaker supports fencing nodes with multiple devices through a feature called fencing topologies.
Simply create the individual devices as you normally would and then define one or more fencing levels in the fencing-topology section in the configuration.
Some possible uses of topologies include:

Table 13.2. Properties of Fencing Levels

Field Description
id
Your name for the level
target
The node to which this level applies
index
The order in which to attempt the levels. Levels are attempted in ascending index order until one succeeds.
devices
A comma-separated list of devices that must all be tried for this level

13.5.1. Example use of Fencing Topologies

 <cib crm_feature_set="3.0.6" validate-with="pacemaker-1.2" admin_epoch="1" epoch="0" num_updates="0">
  <configuration>
    ...
    <fencing-topology>
      <!-- For pcmk-1, try poison-pill and fail back to power -->
      <fencing-level id="f-p1.1" target="pcmk-1" index="1" devices="poison-pill"/>
      <fencing-level id="f-p1.2" target="pcmk-1" index="2" devices="power"/>

      <!-- For pcmk-2, try disk and network, and fail back to power -->
      <fencing-level id="f-p2.1" target="pcmk-2" index="1" devices="disk,network"/>
      <fencing-level id="f-p2.2" target="pcmk-2" index="2" devices="power"/>
    </fencing-topology>
    ...
  <configuration>
  <status/>
</cib>


[16] Not true, since a node or resource must fail before fencing even has a chance to