Maintaining a cluster is a big responsibility. It includes deploying new and updated modules and plugins, applying fixes and improvements, making configuration changes, and more. Maximizing server uptime and minimizing risks take priority when applying changes. Liferay DXP supports standard cluster maintenance techniques, such as rolling restarts.
You should use rolling restarts if possible as it maximizes uptime and mitigates risks of changes harming your deployment. Other techniques include
- Cluster code changes.
- Non-revertible fix packs.
- Module/plugin data changes (modifying data in existing columns).
- Module/plugin data schema changes that break compatibility with the existing version. Breaking changes include but are not limited to dropping columns, changing column types, and changing data formats used in columns (such as changing from XML to JSON).
- Updating a data schema to a version outside of a Service Builder service module’s required data schema range.
Since eligible changes should be done with rolling restarts, it’s explained first.