In today's digital world, ensuring high availability of database systems is essential to keep applications and services continuously accessible and reliable. MariaDB, as a popular open-source relational database system, offers a variety of features and techniques to achieve high availability. In this article, we'll explore some of the best practices that should be implemented to ensure high availability in MariaDB.

Replication

Replication is the fundamental building block for achieving high availability. MariaDB supports several types of replication, including standard row-based replication, statement-based replication, and page-based replication. For high availability, it's recommended to use row-based replication as it minimizes the risk of data inconsistencies between the primary and secondary servers.

• Master-Slave Configuration: The most common configuration is master-slave, where the master server handles all write operations and slave servers are used for reads and as a backup for failover.
• Automatic Failover: For automatic failover, third-party tools like MariaDB Replication Manager or Orchestrator can be used, which automatically promote a slave server to master in case of primary server failure.

Clusters

MariaDB Galera Cluster is a clustering technology that synchronizes data between nodes in real-time, ensuring that all nodes always have the same version of data. This technology allows both reading and writing from any node in the cluster, thereby increasing availability and fault tolerance.

• Minimum Three Nodes: To ensure high availability and resistance to network partitioning (split-brain scenario), it's recommended to have a minimum of three nodes in the cluster.
• Load Balancing: To distribute load among nodes in the cluster, it's advisable to use a load balancer such as HAProxy or MaxScale. These tools also support automatic failover, ensuring clients are connected to available nodes.

Backup and Recovery

Regular backups are crucial for high availability as they enable quick recovery in case of data loss. MariaDB offers tools like mariabackup or mysqldump for database backups.

• Hot Backups: Mariabackup allows for hot backups, meaning the database can be backed up without interrupting operations.
• Point-in-Time Recovery (PITR): For recovery after a failure or data loss, Point-in-Time Recovery technique can be used to restore the database to a specific point in time.

Monitoring and Maintenance

Proactive monitoring and regular maintenance are essential for maintaining high availability. Using monitoring tools such as Monyog or Prometheus with Grafana can help identify potential issues before they cause service outage.

• Regular Health Checks: Monitoring load, disk space usage, replication status, and query performance can help prevent problems.
• Performance Optimization: Regular review and optimization of configuration settings, indexes, and queries can significantly improve the performance and availability of the database system.

By implementing these best practices, you can significantly increase the availability of your MariaDB database and ensure that your applications remain reliable and accessible to users even in the event of unexpected events.