High Availability Cluster Software

What is High Availability Cluster Software?

High availability cluster software manages servers that are grouped together to provide continuous availability, eliminating a single point of failure. This configuration of shared resources is referred to as high availability clusters (HA Clusters) or failover clusters.

This automated approach ensures continuous application availability without the need for manual oversight or intervention. The software notes when a server supporting an application or service fails. It uses a ‘heartbeat technique’ to monitor cluster node health through a dedicated network connection. Each node in the cluster sends a ‘heartbeat’ to the others advertising its availability. Once a failing node is detected, the high availability cluster software immediately restarts the process on another server.

The software helps optimize performance throughout the cluster. Successful high availability cluster implementations are dependent on an IT architecture that addresses load balancing, shared storage, data scalability, multiple networks, geographical diversity, backup, and recovery.

Application Delivery Controllers (ADCs), Load Balancing Software, and high availability software are closely connected. ADCs and load balancing software distribute workloads across multiple servers to improve performance. High availability cluster software combines multiple servers to function as a single entity.

High availability cluster software functionality can be deployed in your on-premises IT infrastructure or utilized as a part of services offered by a cloud provider.

High availability clusters help ensure your systems, databases, and applications are always available to its users when needed. They are especially important in supporting mission-critical applications such as financial transaction processing, database processing, and eCommerce.

High Availability Cluster Software Features

High availability cluster software will include these features.’

• Eliminates single point of failure
• Automatically detects application failures regardless of the cause
• Automates failover of the application to another host
• Prevents data loss during a system failure
• Restarts or ‘repairs’ the failed server without requiring manual intervention
• Manually failover to support planned maintenance

High Availability Cluster Software Comparison

Consider the following before deploying high availability cluster software.

Cost: High availability clusters are more costly and complex than un-clustered server installations. Cost, complexity, and IT support requirements increase dramatically with cluster size growth. Validate that any decision to go with high availability clusters is justified by your organization’s need for continuous availability to support its applications and services.

High Availability Cluster Software vs Fault-Tolerant Hardware Solutions

Fault tolerance is the pinnacle of high availability. High availability cluster software focuses on delivering the minimal possible downtime, fault-tolerant hardware aims to deliver zero downtime. Fault-tolerant server components are duplexed, the two CPUs are kept in lockstep, and if there is a failure the backup immediately takes over. These servers are more expensive than servers that can be used for high availability software clustering.

Pricing Information

Vendors sometimes offer free high availability clustering software to support licensed users of their server platforms or databases. When there is the necessity to pay for this software vendors will provide a price quote. The costs for an on-premises installation of high availability clusters will mostly come from server-related costs and tech support. When taking advantage of high availability clusters in the cloud, the cloud providers charge for the resources that are consumed.