Cross-Cluster Quorum Server Configuration

Cross Cluster Quorum Server Configurations
2 10/7/2004
• Run cluster 2.
• Halt cluster 1.
• Configure cluster 1 as a two node (or more) cluster.
• Configure a Quorum Server package on cluster 1.
• Run cluster 1.
Please refer to section 4 for the detailed steps for this procedure.
3. Considerations for a Cross Cluster Quorum Server Configuration
There are some considerations to use a Cross Cluster Quorum Server configuration.
To configure or reconfigure the cluster with Quorum Server using cmquerycl, cmapplyconf or
cmcheckconf, the Quorum Server must be running. Therefore, when one of the clusters is not running
due to maintenance or failure, the following issues can occur on the other cluster(s):
• If a failure event causes a cluster reformation to occur on the other cluster, all nodes in the other
cluster will TOC, because they cannot communicate with the Quorum Server.
• It will not be possible to configure or reconfigure the cluster using the Quorum Server. The
cmquerycl, cmapplyconf and cmcheckconf commands on the other cluster node will fail, since
they cannot communicate with the Quorum Server.
To avoid these issues, HP still recommends to configure a Quorum Server in one of the following
ways:
• A one node cluster that has a Quorum Server package on it.
• A two (or more) node cluster using a cluster lock disk, that has a Quorum Server package on it.
• Run the Quorum Server independently of Serviceguard, so that the other cluster nodes can use
the Quorum Server.
If each cluster node has only one power input, each node should be connected to a separate power
circuit.
In Figure 1 below, when nodes B and D share the same power circuits (power 2) and that power
circuit fails, nodes B and D will go down. Then, nodes A and C each start cluster reformation.
However, the Quorum Servers running on nodes B and D cannot move to nodes A and C until the
cluster reformation has completed, and the cluster reformation cannot complete on nodes A and C
until they can contact their respective Quorum Servers, so nodes A and C will TOC.