FENCE_ACK_MANUAL(8) cluster FENCE_ACK_MANUAL(8)NAME
fence_ack_manual - a program to override fenced fencing operations
SYNOPSIS
fence_ack_manual [OPTIONS] nodename
DESCRIPTION
When fenced(8) fails to fence a node, it retries indefinately. fence_ack_manual(8) tells fenced to stop retrying and consider the node
fenced.
It is important that this only be done after the node has been manually turned off or prevented from writing to shared storage. Without
this manual action and verification, the storage that fencing protects may become corrupted.
When fenced fences a node that has no fence devices defined in the cluster configuration, the fencing operation fails. This failure will
be repeated indefinately until fence_ack_manual is run by an operator to indicate the node is in a safe state to proceed. (Defining no
fencing devices for node is the equivalent of using the fence_manual agent in previous versions.)
OPTIONS -h Print a help message describing available options, then exit.
SEE ALSO fenced(8)cluster 2009-12-21 FENCE_ACK_MANUAL(8)
Check Out this Related Man Page
FENCE_NODE(8) cluster FENCE_NODE(8)NAME
fence_node - a utility to run fence agents
SYNOPSIS
fence_node [OPTIONS] nodename
DESCRIPTION
This utility runs a fence agent against nodename. The agent and args are taken from the running cluster configuration based on clus-
ter.conf(5).
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 page.
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 configured 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:
Fencing
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).
Unfencing
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).
OPTIONS -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.
FILES
The Unfencing/unfence_node() configuration is very similar to the Fencing/fence_node() configuration shown in fenced(8). Unfencing is only
performed for a node with an <unfence> section:
<clusternode name="node1" nodeid="1">
<fence>
</fence>
<unfence>
</unfence>
</clusternode>
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">
<fence>
<method name="1">
<device name="myswitch" foo="x"/>
</method>
</fence>
<unfence>
<device name="myswitch" foo="x" action="on"/>
</unfence>
</clusternode>
SEE ALSO fenced(8)cluster 2009-12-21 FENCE_NODE(8)