AiVibeHigh Availability (HA)
High availability (HA) is the design of IT and industrial systems to keep running with minimal downtime by removing single points of failure through redundancy, replication and automatic failover.
High availability (HA) is the design of systems to remain operational for a very high proportion of time by eliminating single points of failure and recovering automatically from component faults. Techniques include redundant servers, power supplies and network paths, clustering, load balancing across multiple instances, data replication and health checks that trigger automatic failover. Availability is commonly expressed as a percentage of uptime, such as 99.9 or 99.99 per cent, often called three nines or four nines.
HA is required for systems whose outages cause significant financial, safety or reputational impact, such as payment platforms, telecom networks, hospital systems and production-critical plant applications like MES, SCADA servers and historians. In the cloud, the standard pattern is deploying redundant instances across multiple availability zones behind a load balancer, with managed databases running standby replicas.
Each additional nine of availability requires substantially more cost and engineering effort, so targets should follow business need. HA protects against component and site failures but not against data corruption, faulty releases or region-wide events, which require backups and disaster recovery. Availability can be calculated from mean time between failures and mean time to repair, and it is usually tracked against service level objectives.
Key points
- Removes single points of failure through redundancy and automatic failover
- Availability is expressed as a percentage of uptime, such as 99.9 or 99.99 per cent
- Cloud HA typically spreads instances across availability zones behind a load balancer
- HA does not replace backups or disaster recovery for corruption and regional events
Where AiVibe comes in
AiVibe Software Services delivers cloud solutions on AWS, Microsoft Azure, Google Cloud or on-premise, together with cloud security, legacy modernisation, data analytics and AI and machine learning services.
Related terms
- Availability Zone (AZ)Cloud & AI Infrastructure
- Load BalancingCloud & AI Infrastructure
- Disaster Recovery (DR)Cloud & AI Infrastructure
- Mean Time Between Failures (MTBF)Quality, Reliability & Maintenance
- Mean Time to Repair (MTTR)Quality, Reliability & Maintenance
- Service Level Objective (SLO)Cloud & AI Infrastructure
Terms that refer to High Availability (HA)
- Auto ScalingCloud & AI Infrastructure
- Blue-Green DeploymentCloud & AI Infrastructure
- Cloud RegionCloud & AI Infrastructure
- Managed Database (DBaaS)Cloud & AI Infrastructure
- Recovery Time Objective (RTO)Cloud & AI Infrastructure
- Site Reliability Engineering (SRE)Cloud & AI Infrastructure
- Virtual Machine (VM)Cloud & AI Infrastructure