Which STONITH hardware for power fencing

electrical-powerhardwarehigh-availabilityiloipmi

I'd like to setup a two node high availability cluster using corosync/pacemaker/drbd. For that, of course, I need fencing. As far as I understand, all IPMI/iLO/… solutions do the job, but only as long as the chassis has power. In the case that node B loses power, node A does not have any chance of using STONITH against node B.

What kind of hardware solves this problem? Is there a (standard rack) server which provides IPMI/iLO/… hardware running on battery? Should I use a network-connected UPS?

Best Answer

You can configure the iLO/IPMI based fencing, and then using for example fence_apc fencing agent with an APC power switch as a secondary fence device. That way, if the server loses power, then the secondary fencing agent is still able to STONITH the server in a way that makes sense to the cluster.

like described here:

A node can have multiple fence methods and each fence method can have multiple fence devices.

Multiple fence methods are set up for redundancy/insurance. For example, you may be using a baseboard management fencing method for a node in your cluster such as IPMI, or iLO, or RSA, or DRAC. All of these depend on a network connection. If this connection would fail, fencing could not occur, so as a backup fence method you could declare a second method of fencing that used a power switch or somesuch to fence the node. If the first method failed to fence the node, the second fence method would be employed.

You can also consider adding fence_manual as a secondary fencing agent, that way you can always recover your cluster, but manual intervention will then of course be required.

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