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7
Adding or Modifying Resource
Agents
All tasks that need to be managed by a cluster must be available as a resource. There
are two major groups here to consider: resource agents and STONITH agents. For both
categories, you can add your own agents, extending the abilities of the cluster to your
own needs.
7.1 STONITH Agents
A cluster sometimes detects that one of the nodes is behaving strangely and needs to
remove it. This is called fencing and is commonly done with a STONITH resource. All
STONITH resources reside in
/usr/lib/stonith/plugins
on each node.
WARNING: SSH and STONITH Are Not Supported
It is impossible to know how SSH might react to other system problems. For
this reason, SSH and STONITH agent are not supported for production environ-
ments.
To get a list of all currently available STONITH devices (from the software side), use
the command
stonith -L
.
As of yet there is no documentation about writing STONITH agents. If you want to
write new STONITH agents, consult the examples available in the source of the
heartbeat-common
package.
Adding or Modifying Resource Agents 79