Quorum Devices

Sun Cluster configurations use quorum devices to maintain data and resource integrity. If the cluster temporarily loses connection to a node, the quorum device prevents amnesia or split-brain problems when the cluster node attempts to rejoin the cluster. During Sun Cluster installation of a two-node cluster, the scinstall utility automatically configures a quorum device. The quorum device is chosen from the available shared storage disks. The scinstall utility assumes that all available shared storage disks are supported to be quorum devices. After installation, you can also configure additional quorum devices by using the scsetup(1M) utility.

You do not need to configure quorum devices for a single-node cluster.

If your cluster configuration includes third-party shared storage devices that are not supported for use as quorum devices, you must use the scsetup utility to configure quorum manually.

Consider the following points when you plan quorum devices.

• Minimum – A two-node cluster must have at least one quorum device, which can be a shared disk or a Network Appliance NAS device. For other topologies, quorum devices are optional.

• Odd-number rule – If more than one quorum device is configured in a two-node cluster, or in a pair of nodes directly connected to the quorum device, configure an odd number of quorum devices. This configuration ensures that the quorum devices have completely independent failure pathways.

• Connection – You must connect a quorum device to at least two nodes.

For more information about quorum devices, see Quorum and Quorum Devices in Sun Cluster Concepts Guide for Solaris OS and Quorum Devices in Sun Cluster Overview for Solaris OS.