High Availability and Disaster Recovery for Systems
High Availability and Disaster Recovery for Systems Systems need to stay online when parts fail. High availability and disaster recovery are two related goals that protect users and data. A thoughtful design reduces downtime, lowers risk, and speeds recovery after incidents. The right blend depends on your services, budget, and tolerance for disruption. Core ideas High availability aims for minimal downtime through design, redundancy, and fast auto failover. Disaster recovery plans cover larger events, with measured RPO (recovery point objective) and RTO (recovery time objective). Data replication, health checks, and clear runbooks are essential to keep services resilient. Practical patterns Active-active across regions: multiple live instances share load and stay in sync, ready to serve if one region fails. Active-passive with warm standby: a ready-to-go duplicate that takes over quickly when needed. Local redundancy with cloud services: redundant components inside a single location or cloud region. Backups and restore tests: frequent backups plus regular drills to verify data can be restored. Synchronous vs asynchronous replication: sync reduces data loss but may add latency; async is faster for users but risks some data loss. Implementation guidance Start with clear targets: define RPO and RTO for each critical service, then match a pattern to that risk level. Use automated health checks, load balancing, and health-based failover to switch traffic without human delay. Maintain data replication across regions or sites and test the entire chain from monitoring to restore. ...