The two broad categories of fence device are power fencing, which cuts off power to the target, and fabric fencing, which cuts off the target’s access to some critical resource, such as a shared disk or access to the local network.

Power fencing devices include:

Fabric fencing devices include:

Using IPMI as a power fencing device may seem like a good choice. However, if the IPMI shares power and/or network access with the host (such as most onboard IPMI controllers), a power or network failure will cause both the host and its fencing device to fail. The cluster will be unable to recover, and must stop all resources to avoid a possible split-brain situation.

Likewise, any device that relies on the machine being active (such as SSH-based "devices" sometimes used during testing) is inappropriate, because fencing will be required when the node is completely unresponsive.