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FENCE_NODE(8)			    cluster			 FENCE_NODE(8)

       fence_node - a utility to run fence agents

       fence_node [OPTIONS] nodename

       This  utility  runs a fence agent against nodename.  The agent and args
       are taken  from	the  running  cluster  configuration  based  on	 clus‐

       fence_node is a wrapper around the libfence functions: fence_node() and
       unfence_node().	These libfence functions use libccs to read  the  node
       fencing	configuration,	which  means that corosync (with cman and ccs)
       must be running to use fence_node(8).

       The fenced(8) daemon is the main user of libfence:fence_node(), and the
       configuration  details for that function are given in the fenced(8) man

   Fencing vs. Unfencing
       The main use for unfencing is with storage/SAN (non-power) agents.

       When using power-based fencing agents, the  fencing  action  itself  is
       supposed to turn a node back on after first turning the power off (this
       happens automatically with a "reboot" action, and needs to  be  config‐
       ured explicitly as "off" + "on" otherwise.)

       When  using  storage-based  fencing  agents,  the fencing action is not
       allowed to re-enable a node after disabling it.	Re-enabling  a	fenced
       node  is	 only  safe once the node has been rebooted.  A natural way to
       re-enable a fenced node's access to storage, is for that	 node  to  re-
       enable  the  access  itself  during its startup process.	 The cman init
       script calls fence_node -U (nodename defaults to	 local	nodename  when
       unfencing).   Unfencing	a node without an <unfence> configuration (see
       below) is a no-op.

       The basic differences between fencing and unfencing:


       1. libfence: fence_node(), command line: fence_node nodename

       2. Turns off or disables a node.

       3. Agents run with the default action of "off", "disable" or "reboot".

       4. Performed by a cluster node against another node that fails (by  the
	  fenced daemon).


       1. libfence: unfence_node(), command line: fence_node -U nodename

       2. Turns on or enables a node.

       3. Agents run with the explicit action of "on" or "enable".

       4. Performed  by a cluster node "against" itself during startup (by the
	  cman init script).

       -U     Unfence the node, default local node name.

       -v     Show fence agent results, -vv to also show agent args.

       -h     Print a help message describing available options, then exit.

       -V     Print program version information, then exit.

       The Unfencing/unfence_node() configuration is very similar to the Fenc‐
       ing/fence_node()	 configuration	shown in fenced(8).  Unfencing is only
       performed for a node with an <unfence> section:

       <clusternode name="node1" nodeid="1">

       The <unfence> section does  not	contain	 <method>  sections  like  the
       <fence>	section does.  It contains <device> references directly, which
       mirror the corresponding device sections for <fence>, with the  notable
       addition	 of  the  explicit  action  of	"on"  or  "enable".   The same
       <fencedevice> is referenced by both fence and unfence  <device>	lines,
       and the same per-node args should be repeated.

       <clusternode name="node1" nodeid="1">
	       <method name="1">
	       <device name="myswitch" foo="x"/>

	       <device name="myswitch" foo="x" action="on"/>


cluster				  2009-12-21			 FENCE_NODE(8)

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