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For initial tests outside of a productive environment, you may utilize fence_manual (which is default if all fencing devices would fail for some reason).
To upgrade nodes with a fencing device, apc network managed power switches are imho an ideal solution. They are reliable, rather inexpensive (though they still cost ~300 EUR) and easy to setup.
Other common methods are management adapters like HP Integrated Lights Out module (ILO) or Intelligent Platform Management Interface (IPMI) for a broader spectrum of servers (even cheap servers are shipped with them on board).
For productive environments you should use 2 or more fencing devices.
Other methods also include zoning (i.e. deactivating the port of some fibre channel switch) but they are not so common.
Oracle Clusterware supports node suicide as fencing method. That means that the cluster node is told to reboot in case the other nodes think there is a sick node present that must leave the cluster.
Anyway, Red Hat Cluster Suite does not support this as reliable method and in most cases uses methods to power cycle the node.
You can write your own fencing method that reboots the node / creates a kernel panic, though. However it is very unlikely that this would ever be supported by Red Hat.
My cluster is on 2 virtual machines on the same computer, the problem with that that except the manual fencing nothing form the fencing devices in conga or sys-conf-clus. works.
I fond fence_xen (if you google it its the first result), the problem is that I don,t know perl so I have no idea what it does.
Another problem is that if you want to manage your cluster with luci you must chose the fencing from the drop box, if you put it in the cluster.conf buy your self luci doesn't like it.
So how can you add a fencing device to the drop box?
Is it possible to write fencing device using bash? All I need it to do is: destroy/create domain (with xm command i think) and start (run) the virtual machine
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