Introduction to the Sun Cluster Environment

The Sun Cluster environment extends the Solaris Operating System into a cluster operating system. A cluster is a collection of one or more nodes that belong exclusively to that collection. In a cluster that runs on the Solaris 10 OS, a global cluster and a zone cluster are types of clusters.

In a cluster that runs on any version of the Solaris OS that was released before the Solaris 10 OS, a node is a physical machine that contributes to cluster membership and is not a quorum device. In a cluster that runs on the Solaris 10 OS, the concept of a node changes. In this environment, a node is a Solaris zone that is associated with a cluster. In this environment, a Solaris host, or simply host, is one of the following hardware or software configurations that runs the Solaris OS and its own processes:

• A “bare metal” physical machine that is not configured with a virtual machine or as a hardware domain

• A Sun Logical Domains (LDoms) guest domain

• A Sun Logical Domains (LDoms) I/O domain

• A hardware domain

These processes communicate with one another to form what looks like (to a network client) a single system that cooperatively provides applications, system resources, and data to users.

In a Solaris 10 environment, a global cluster is a type of cluster that is composed only of one or more global-cluster voting nodes and optionally, zero or more global-cluster non-voting nodes.

A global cluster can optionally also include solaris8, solaris9, lx (Linux), or native brand, non-global zones that are not nodes, but high availability containers (as resources).

A global-cluster voting node is a native brand, global zone in a global cluster that contributes votes to the total number of quorum votes, that is, membership votes in the cluster. This total determines whether the cluster has sufficient votes to continue operating. A global-cluster non-voting node is a native brand, non-global zone in a global cluster that does not contribute votes to the total number of quorum votes, that is, membership votes in the cluster.

In a Solaris 10 environment, a zone cluster is a type of cluster that is composed only of one or more cluster brand, voting nodes. A zone cluster depends on, and therefore requires, a global cluster. A global cluster does not contain a zone cluster. You cannot configure a zone cluster without a global cluster. A zone cluster has, at most, one zone cluster node on a machine.

A zone-cluster node continues to operate only as long as the global-cluster voting node on the same machine continues to operate. If a global-cluster voting node on a machine fails, all zone-cluster nodes on that machine fail as well.

A cluster offers several advantages over traditional single-server systems. These advantages include support for failover and scalable services, capacity for modular growth, and low entry price compared to traditional hardware fault-tolerant systems.

The goals of the Sun Cluster software are:

• Reduce or eliminate system downtime because of software or hardware failure

• Ensure availability of data and applications to end users, regardless of the kind of failure that would normally take down a single-server system

• Increase application throughput by enabling services to scale to additional processors by adding nodes to the cluster

• Provide enhanced availability of the system by enabling you to perform maintenance without shutting down the entire cluster

For more information about fault tolerance and high availability, see Making Applications Highly Available With Sun Cluster in Sun Cluster Overview for Solaris OS.

Refer to High Availability FAQs for questions and answers on high availability.