Chapter 1

Introduction and Overview

The SunPlex system is an integrated hardware and Sun Cluster software solution that is used to create highly available and scalable services.

Sun Cluster 3.1 10/03 Concepts Guide provides the conceptual information needed by the primary audience for SunPlex documentation. This audience includes

Service providers who install and service cluster hardware
System administrators who install, configure, and administer Sun Cluster software
Application developers who develop failover and scalable services for applications not currently included with the Sun Cluster product

This book works with the rest of the SunPlex documentation set to provide a complete view of the SunPlex system.

This chapter

Provides an introduction and high-level overview of the SunPlex system
Describes the several viewpoints of the SunPlex audience
Identifies key concepts you need to understand before working with the SunPlex system
Maps key concepts to the SunPlex documentation that includes procedures and related information
Maps cluster-related tasks to the documentation containing procedures used to accomplish those tasks

Introduction to the SunPlex System

The SunPlex system extends the Solaris operating environment into a cluster operating system. A cluster, or plex, is a collection of loosely coupled computing nodes that provides a single client view of network services or applications, including databases, web services, and file services.

Each cluster node is a standalone server that runs its own processes. 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.

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 SunPlex system 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

High Availability Versus Fault Tolerance

The SunPlex system is designed as a highly available (HA) system, that is, a system that provides near continuous access to data and applications.

By contrast, fault-tolerant hardware systems provide constant access to data and applications, but at a higher cost because of specialized hardware. Additionally, fault-tolerant systems usually do not account for software failures.

The SunPlex system achieves high availability through a combination of hardware and software. Redundant cluster interconnects, storage, and public networks protect against single points of failure. The cluster software continuously monitors the health of member nodes and prevents failing nodes from participating in the cluster to protect against data corruption. Also, the cluster monitors services and their dependent system resources, and fails over or restarts services in case of failures.

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

Failover and Scalability in the SunPlex System

The SunPlex system enables you to implement either failover or scalable services. In general, a failover service provides only high availability (redundancy), whereas a scalable service provides high availability along with increased performance. A single cluster can support both failover and scalable services.

Failover Services

Failover is the process by which the cluster automatically relocates a service from a failed primary node to a designated secondary node. With failover, Sun Cluster software provides high availability.

When a failover occurs, clients might see a brief interruption in service and might need to reconnect after the failover has finished. However, clients are not aware of the physical server that provides the service.

Scalable Services

While failover is concerned with redundancy, scalability provides constant response time or throughput without regard to load. A scalable service leverages the multiple nodes in a cluster to concurrently run an application, thus providing increased performance. In a scalable configuration, each node in the cluster can provide data and process client requests.

Refer to Data Services for more specific information on failover and scalable services.

Three Viewpoints of the SunPlex System

This section describes three different viewpoints on the SunPlex system and the key concepts and documentation relevant to each viewpoint. These viewpoints come from:

Hardware installation and service personnel
System administrators
Application programmers

Hardware Installation and Service Viewpoint

To hardware service professionals, the SunPlex system looks like a collection of off-the-shelf hardware that includes servers, networks, and storage. These components are all cabled together so that every component has a backup and no single point of failure exists.

Key Concepts - Hardware

Hardware service people need to understand the following cluster concepts.

Cluster hardware configurations and cabling
Installing and servicing (adding, removing, replacing):
- Network interface components (adapters, junctions, cables)
- Disk interface cards
- Disk arrays
- Disk drives
- The administrative console and the console access device
Setting up the administrative console and console access device


	Chapter 1 Introduction and Overview The SunPlex system is an integrated hardware and Sun Cluster software solution that is used to create highly available and scalable services. Sun Cluster 3.1 10/03 Concepts Guide provides the conceptual information needed by the primary audience for SunPlex documentation. This audience includes Service providers who install and service cluster hardware System administrators who install, configure, and administer Sun Cluster software Application developers who develop failover and scalable services for applications not currently included with the Sun Cluster product This book works with the rest of the SunPlex documentation set to provide a complete view of the SunPlex system. This chapter Provides an introduction and high-level overview of the SunPlex system Describes the several viewpoints of the SunPlex audience Identifies key concepts you need to understand before working with the SunPlex system Maps key concepts to the SunPlex documentation that includes procedures and related information Maps cluster-related tasks to the documentation containing procedures used to accomplish those tasks Introduction to the SunPlex System The SunPlex system extends the Solaris operating environment into a cluster operating system. A cluster, or plex, is a collection of loosely coupled computing nodes that provides a single client view of network services or applications, including databases, web services, and file services. Each cluster node is a standalone server that runs its own processes. 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. 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 SunPlex system 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 High Availability Versus Fault Tolerance The SunPlex system is designed as a highly available (HA) system, that is, a system that provides near continuous access to data and applications. By contrast, fault-tolerant hardware systems provide constant access to data and applications, but at a higher cost because of specialized hardware. Additionally, fault-tolerant systems usually do not account for software failures. The SunPlex system achieves high availability through a combination of hardware and software. Redundant cluster interconnects, storage, and public networks protect against single points of failure. The cluster software continuously monitors the health of member nodes and prevents failing nodes from participating in the cluster to protect against data corruption. Also, the cluster monitors services and their dependent system resources, and fails over or restarts services in case of failures. Refer to High Availability FAQs for questions and answers on high availability. Failover and Scalability in the SunPlex System The SunPlex system enables you to implement either failover or scalable services. In general, a failover service provides only high availability (redundancy), whereas a scalable service provides high availability along with increased performance. A single cluster can support both failover and scalable services. Failover Services Failover is the process by which the cluster automatically relocates a service from a failed primary node to a designated secondary node. With failover, Sun Cluster software provides high availability. When a failover occurs, clients might see a brief interruption in service and might need to reconnect after the failover has finished. However, clients are not aware of the physical server that provides the service. Scalable Services While failover is concerned with redundancy, scalability provides constant response time or throughput without regard to load. A scalable service leverages the multiple nodes in a cluster to concurrently run an application, thus providing increased performance. In a scalable configuration, each node in the cluster can provide data and process client requests. Refer to Data Services for more specific information on failover and scalable services. Three Viewpoints of the SunPlex System This section describes three different viewpoints on the SunPlex system and the key concepts and documentation relevant to each viewpoint. These viewpoints come from: Hardware installation and service personnel System administrators Application programmers Hardware Installation and Service Viewpoint To hardware service professionals, the SunPlex system looks like a collection of off-the-shelf hardware that includes servers, networks, and storage. These components are all cabled together so that every component has a backup and no single point of failure exists. Key Concepts - Hardware Hardware service people need to understand the following cluster concepts. Cluster hardware configurations and cabling Installing and servicing (adding, removing, replacing): Network interface components (adapters, junctions, cables) Disk interface cards Disk arrays Disk drives The administrative console and the console access device Setting up the administrative console and console access device