Novell LINUX ENTERPRISE 11 - HIGH AVAILABILITY, Manual, Page: 92 / 298

The resource level fencing may be achieved using normal resources on which the
resource you want to protect depends. Such a resource would simply refuse to start
on this node and therefore resources which depend on will not run on the same
node.
Node Level Fencing
Node level fencing ensures that a node does not run any resources at all. This is
usually done in a very simple, yet abrupt way: the node is reset using a power
switch. This is necessary when the node becomes unresponsive.
8.2 Node Level Fencing
In SUSE® Linux Enterprise High Availability Extension, the fencing implementation
is STONITH (Shoot The Other Node in the Head). It provides the node level fencing.
The High Availability Extension includes the
stonith
command line tool, an exten-
sible interface for remotely powering down a node in the cluster. For an overview of
the available options, run
stonith --help
or refer to the man page of
stonith
for more information.
8.2.1 STONITH Devices
To use node level fencing, you first need to have a fencing device. To get a list of
STONITH devices which are supported by the High Availability Extension, run the
following command as
root
on any of the nodes:
stonith -L
STONITH devices may be classified into the following categories:
Power Distribution Units (PDU)
Power Distribution Units are an essential element in managing power capacity and
functionality for critical network, server and data center equipment. They can pro-
vide remote load monitoring of connected equipment and individual outlet power
control for remote power recycling.
Uninterruptible Power Supplies (UPS)
A stable power supply provides emergency power to connected equipment by
supplying power from a separate source in the event of utility power failure.
82 High Availability Guide