1FENCE_NODE(8) cluster FENCE_NODE(8)
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6 fence_node - a utility to run fence agents
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10 fence_node [OPTIONS] nodename
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14 This utility runs a fence agent against nodename. The agent and args
15 are taken from the running cluster configuration based on clus‐
16 ter.conf(5).
17 fence_node is a wrapper around the libfence functions: fence_node() and
20 unfence_node(). These libfence functions use libccs to read the node
21 fencing configuration, which means that corosync (with cman and ccs)
22 must be running to use fence_node(8).
23 The fenced(8) daemon is the main user of libfence:fence_node(), and the
26 configuration details for that function are given in the fenced(8) man
27 page.
28 Fencing vs. Unfencing
31 The main use for unfencing is with storage/SAN (non-power) agents.
32 When using power-based fencing agents, the fencing action itself is
35 supposed to turn a node back on after first turning the power off (this
36 happens automatically with a "reboot" action, and needs to be config‐
37 ured explicitly as "off" + "on" otherwise.)
38 When using storage-based fencing agents, the fencing action is not
41 allowed to re-enable a node after disabling it. Re-enabling a fenced
42 node is only safe once the node has been rebooted. A natural way to
43 re-enable a fenced node's access to storage, is for that node to re-
44 enable the access itself during its startup process. The cman init
45 script calls fence_node -U (nodename defaults to local nodename when
46 unfencing). Unfencing a node without an <unfence> configuration (see
47 below) is a no-op.
48 The basic differences between fencing and unfencing:
51 Fencing
53 1. libfence: fence_node(), command line: fence_node nodename
55 2. Turns off or disables a node.
57 3. Agents run with the default action of "off", "disable" or "reboot".
59 4. Performed by a cluster node against another node that fails (by the
61 fenced daemon).
62 Unfencing
64 1. libfence: unfence_node(), command line: fence_node -U nodename
66 2. Turns on or enables a node.
68 3. Agents run with the explicit action of "on" or "enable".
70 4. Performed by a cluster node "against" itself during startup (by the
72 cman init script).
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76 -U Unfence the node, default local node name.
77 -v Show fence agent results, -vv to also show agent args.
79 -h Print a help message describing available options, then exit.
81 -V Print program version information, then exit.
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86 The Unfencing/unfence_node() configuration is very similar to the Fenc‐
87 ing/fence_node() configuration shown in fenced(8). Unfencing is only
88 performed for a node with an <unfence> section:
89 <clusternode name="node1" nodeid="1">
91 <fence>
92 </fence>
93 <unfence>
94 </unfence>
95 </clusternode>
96 The <unfence> section does not contain <method> sections like the
98 <fence> section does. It contains <device> references directly, which
99 mirror the corresponding device sections for <fence>, with the notable
100 addition of the explicit action of "on" or "enable". The same
101 <fencedevice> is referenced by both fence and unfence <device> lines,
102 and the same per-node args should be repeated.
103 <clusternode name="node1" nodeid="1">
105 <fence>
106 <method name="1">
107 <device name="myswitch" foo="x"/>
108 </method>
109 </fence>
110 <unfence>
112 <device name="myswitch" foo="x" action="on"/>
113 </unfence>
114 </clusternode>
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118 fenced(8)
119cluster 2009-12-21 FENCE_NODE(8)