What about High Availability?
High Availability (HA) is crucial for critical infrastructure, medical facilities, logistics centers, business-critical services, banking institutions, and more. All these sectors are sensitive to failures and interruptions in their operations. Here are several steps to address the most pressing HA issues and ultimately achieve the highest level of availability and fault tolerance in your infrastructure.
Step 1 — Ensure physical resource redundancy/excess: Due to resource shortages, various replicas of databases or infrastructure nodes may run on the same physical nodes. In the case of a working node failure, both primary and backup replicas become inaccessible. A strategic perspective involves gradually distributing replicas across different nodes, later across different buildings in a data center, or even geographically distant data centers if possible.
Step 2 — Implement a thoughtful network architecture: An ill-considered network architecture may lead to bandwidth bottlenecks, especially during replica synchronization. Desynchronization of database replicas poses significant threats to the entire system. It is essential to have a network architecture development plan in place and to expand the network according to increasing loads.
Step 3 — Synchronize file storage at the application level: Overreliance on disk storage (SAN) or improper use of disk RAID arrays may compromise high availability. Disk arrays aren’t always a good solution because the controllers that manage storage information, are typically a single point of failure. Therefore, it is better to ensure file storage synchronization at the application level where possible during backup storage, etc.
Step 4 — Utilize troubleshooting for practical HA architecture issue detection: Troubleshooting helps identify why something isn’t working as expected and provides insights on how to resolve the issue. Regular stress tests, including simulated server shutdowns or resets, allowing you to explore how the HA mechanism responds to real failure scenarios.
Additional Considerations: Incompatibility of the application with high availability requirements due to issues such as data access blocking, threads, or caching can be an unexpected obstacle. It is crucial to address these problems.
As the level of HA increases, Disaster Recovery (DR) should also be elevated. A high-availability environment won’t help recover lost data in case of a massive failure, so it’s better to implement a high level of Disaster Recovery step by step. Also, you should have a documented emergency service recovery plan, periodically verifying the functionality of backups, and storing backups in separate data centers.
Achieving high availability requires a holistic approach that combines physical redundancy, network optimization, file storage synchronization, practical issue detection, and a robust disaster recovery plan. These steps will enhance the resilience and reliability of critical infrastructure in the face of potential failures.
