Implement a fencing topology on SLES 11 SP3 / 12 High Availabilty Extension

This document (7016042) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise High Availability Extension 11 Service Pack 3

Situation

In some cases it may be necessary to use more than one fencing mechanism to avoid a single point of failure.

For example: Main fencing mechanism is the libvirt agent (or vcenter, xen etc. ), but in case the VM host ( hypervisor ) is down, fencing via libvirt will never succeed.
The idea is to implement a second fencing mechanism, e.g. IPMI, which will act upon failure of the first one.

Resolution

This is just a small test setup to demonstrate the use of fencing_topology, consisting of one VM host ( 192.168.10.1 ) and two virtual machines, node3 and node4. Fencing mechanisms are ssh (only use in test environments) and libvirt.

The core of the solution is the following paragraph:

fencing_topology \
        node4: fence-node4-ssh fence-node4-libvirt \
        node3: fence-node3-ssh fence-node3-libvirt

meaning: To fence node4 first use the resource fence-node4-ssh, if that fails use the resource fence-node4-libvirt

node 1084754642: node3
node 1084754643: node4
primitive fence-node3-libvirt stonith:external/libvirt \
        params hostlist=node3 hypervisor_uri="qemu+ssh://192.168.10.1/system" reset_method=power_cycle \
        op monitor interval=180 timeout=30 \
        meta target-role=Started
primitive fence-node3-ssh stonith:ssh \
        params hostlist=node3 stonith-timeout=30 \
        meta target-role=Started
primitive fence-node4-libvirt stonith:external/libvirt \
        params hostlist=node4 hypervisor_uri="qemu+ssh://192.168.10.1/system" reset_method=power_cycle \
        op monitor interval=180 timeout=30 \
        meta target-role=Started
primitive fence-node4-ssh stonith:ssh \
        params hostlist=node4 stonith-timeout=30 \
        meta target-role=Started
location loc-fence-node3-libvirt fence-node3-libvirt -inf: node3
location loc-fence-node3-ssh fence-node3-ssh -inf: node3
location loc-fence-node4-libvirt fence-node4-libvirt -inf: node4
location loc-fence-node4-ssh fence-node4-ssh -inf: node4
fencing_topology \
        node4: fence-node4-ssh fence-node4-libvirt \
        node3: fence-node3-ssh fence-node3-libvirt
property cib-bootstrap-options: \
        stonith-enabled=yes \
        no-quorum-policy=ignore \
        placement-strategy=balanced \
        dc-version=1.1.12-ad083a8 \
        cluster-infrastructure=corosync \
        cluster-name=hacluster \
        stonith-timeout=90 \
        last-lrm-refresh=1420721144
rsc_defaults rsc-options: \
        resource-stickiness=1 \
        migration-threshold=3
op_defaults op-options: \
        timeout=600 \
        record-pending=true

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