PostgreSQL High Availability Cluster
I designed and implemented a fault-tolerant PostgreSQL cluster with automatic failover, achieving 99.99% uptime for a critical financial application.
At a glance
- •99.99% uptime over 18 months
- •Planned maintenance: hours → seconds
- •~$200K annual downtime cost avoided
Problem Statement
A financial services company was dealing with frequent downtime on their single-instance PostgreSQL database, which put them at risk for data loss and service interruptions. They needed automatic failover, replication, and near-zero downtime during maintenance.
Architecture & Design
I implemented a three-node PostgreSQL cluster using Patroni for automatic failover, etcd for distributed configuration, and HAProxy for connection pooling and load balancing. The setup includes synchronous replication to prevent data loss and asynchronous replicas for scaling reads.
Implementation Details
I deployed the cluster using Ansible for infrastructure automation. Set up streaming replication with WAL archiving to S3 for point-in-time recovery. Built comprehensive monitoring with Prometheus and Grafana to track replication lag, connection pools, and query performance. Automated backup procedures with pgBackRest.
Results & Outcome
I achieved 99.99% uptime over 18 months with zero data loss. Planned maintenance went from hours of downtime to just seconds through seamless failover. Read query performance improved 60% with read replica distribution. The client saved about $200K annually in downtime costs.