In the upgrade order of an IDX cluster, which component is upgraded first?

In an indexer cluster, the upgrade order is crucial to maintaining the integrity and availability of data. The Cluster Master is the component that must be upgraded first because it orchestrates the entire indexer cluster, managing the configuration and ensuring that all the indexed data is properly handled.

Upgrading the Cluster Master first allows it to take control of any configuration changes needed for the remaining components, such as the indexers and search heads. Since the Cluster Master is responsible for communicating with the indexers to coordinate the data replication and data distribution processes, its upgrade is critical to ensure that these subsequent upgrades occur seamlessly.

Once the Cluster Master is upgraded, the indexers can be upgraded next, followed by the search heads. If you were to upgrade the indexers or search heads before the Cluster Master, there may be discrepancies or incompatibilities that could lead to issues with data availability or cluster management.

This structured upgrade order helps in minimizing downtime and ensuring that the cluster remains functional throughout the upgrade process.