PowerHA

PowerHA SystemMirror is IBM's high-availability clustering software for IBM Power Systems. It provides automated failover of applications and resources across a cluster of Power-based servers to maintain service continuity in the event of hardware, operating system, or application failures. The software originated from IBM’s HACMP product and has evolved into the PowerHA family, with editions historically focused on AIX and broader support for Linux on Power in later releases.

A PowerHA cluster consists of two or more nodes connected via reliable network paths and shared storage. Key concepts include service groups (or resource groups), which define collections of resources such as file systems, IP addresses, and applications that must fail over together. The cluster uses fencing (to prevent split-brain scenarios) and a quorum mechanism to determine the authoritative cluster state. Resource agents provide the logic needed to manage the lifecycle of individual resources during failover.

Typical deployments use multi-node configurations to support planned maintenance, disaster recovery, or uptime requirements for mission-critical workloads. PowerHA supports automated failover, manual failover, and customizable policies for resource start, stop, and migration. It integrates with storage areas and network infrastructure to ensure that resources rejoin the cluster on an alternate node with minimal downtime, and it offers monitoring and diagnostics tools for cluster health and performance.

Deployment considerations include ensuring compatible shared storage, proper fencing configuration, network reliability, and appropriate licensing. PowerHA is chosen to improve application availability, reduce planned downtime, and support rapid recovery for enterprise workloads on IBM Power Systems.