Elasticsearch 7.0 introduces a revamped cluster coordination subsystem that enhances scalability, safety, and ease of use compared to earlier versions. This new subsystem replaces the Zen Discovery method and removes the need for the minimum_master_nodes setting, instead allowing Elasticsearch to automatically manage quorum settings and voting configurations, thus reducing the risk of misconfigurations that could lead to data loss. The coordination system ensures consistent cluster state updates across nodes, even amidst failures, by electing a master node and using quorum-based acceptance of updates. It also offers improved fault tolerance, faster master elections, and clear logging for troubleshooting. The upgrade from version 6.x to 7.0 can be done via a rolling upgrade or full-cluster restart, with the former allowing for continuous cluster availability. The redesign aligns more closely with distributed consensus theories, ensuring both safety and liveness, while maintaining compatibility with existing Elasticsearch behavior through advanced fault detection and adaptive techniques. The enhancements facilitate zero-downtime upgrades and make cluster management more robust and intuitive.