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 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
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
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.
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 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.
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.
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
To hardware service people, 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.
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
The following sections contain material relevant to the preceding key concepts:
The following SunPlex document includes procedures and information associated with hardware service concepts:
Sun Cluster 3.x Hardware Administration Collection at http://docs.sun.com/db/coll/1024.1
To the system administrator, the SunPlex system looks like a set of servers (nodes) cabled together, sharing storage devices. The system administrator sees:
Specialized cluster software integrated with Solaris software to monitor the connectivity between cluster nodes
Specialized software that monitors the health of user application programs running on the cluster nodes
Volume management software that sets up and administers disks
Specialized cluster software that enables all nodes to access all storage devices, even those not directly connected to disks
Specialized cluster software that enables files to appear on every node as though they were locally attached to that node
System administrators need to understand the following concepts and processes:
The interaction between the hardware and software components
The general flow of how to install and configure the cluster including:
Installing the Solaris operating environment
Installing and configuring Sun Cluster software
Installing and configuring a volume manager
Installing and configuring application software to be cluster ready
Installing and configuring Sun Cluster data service software
Cluster administrative procedures for adding, removing, replacing, and servicing cluster hardware and software components
Configuration modifications to improve performance
The following sections contain material relevant to the preceding key concepts:
The following SunPlex documents include procedures and information associated with the system administration concepts:
The SunPlex system provides data services for such applications as Oracle, NFS, DNS, SunTM ONE Web Server, Apache Web Server, and SunTM ONE Directory Server. Data services are created by configuring an off-the-shelf applications to run under control of the Sun Cluster software. The Sun Cluster software provides configuration files and management methods that start, stop, and monitor the applications. If you need to create a new failover or scalable service, you can use the SunPlex Application Programming Interface (API) and the Data Service Enabling Technologies API (DSET API) to develop the necessary configuration files and management methods that enable its application to run as a data service on the cluster.
Application programmers need to understand the following:
The characteristics of their application to determine whether it can be made to run as a failover or scalable data service.
The Sun Cluster API, DSET API, and the “generic” data service. Programmers need to determine which tool is most suitable for them to use to write programs or scripts to configure their application for the cluster environment.
The following sections contain material relevant to the preceding key concepts:
The following SunPlex documents include procedures and information associated with the application programmer concepts:
Sun Cluster 3.1 Data Service Collection at http://docs.sun.com/db/coll/573.10
Sun Cluster 3.1 Data Service Planning and Administration Guide
All SunPlex system tasks require some conceptual background. The following table provides a high-level view of the tasks and the documentation that describes task steps. The concepts sections in this book describe how the concepts map to these tasks.
Table 1–1 Task Map: Mapping User Tasks to Documentation
To Do This Task... |
Use This Documentation... |
---|---|
Install cluster hardware |
Sun Cluster 3.x Hardware Administration Collection at http://docs.sun.com/db/coll/1024.1/ |
Install Solaris software on the cluster | |
Install SunTM Management Center software | |
Install and configure Sun Cluster software | |
Install and configure volume management software |
Sun Cluster 3.1 Software Installation Guide Your volume management documentation |
Install and configure Sun Cluster data services |
Sun Cluster 3.1 Data Service Planning and Administration Guide |
Service cluster hardware | |
Administer Sun Cluster software | |
Administer volume management software |
Sun Cluster 3.1 System Administration Guide and your volume management documentation |
Administer application software |
Your application documentation |
Problem identification and suggested user actions | |
Create a new data service |