Cluster Persistence, Caching, and Multicast
Cluster persistence, caching, and multicast are stored in the cluster database.
When persistence is enabled, ESP will record which projects and workspaces were in existence when the cluster shuts down. By default, persistence is enabled and configured to record to the cluster database. You can use file-based persistence instead by changing the Persistence Type setting to directory and specifying the directory in the Persistence Directory setting.
When persistence is disabled, you lose all your projects when the last manager node in the cluster shuts down; therefore, in a production system, SAP recommends that you leave cluster persistence enabled.
The cluster cache is an in-memory distributed cache used for internal sharing of cluster state and configuration. Manager nodes are members of the cache, while controller nodes are clients of the cache. Cache properties must be configured for all nodes, but you do not need to provide port information for controller-only nodes. For all nodes added to this cluster, configure the same hostname and port in the Connectivity tab for the node in ESP Cockpit.
- Multicast
- Each manager node broadcasts its connection details so other managers can join if they have the correct credentials. Recommended for testing environments where all nodes in the cluster are on the same subnet. Multicast does not work well when cluster nodes are on different subnets or when multiple clusters use the same names and ports (usually the defaults).
- Direct connect
- Each manager node uses the host name and port information in its Managers section of the cluster configuration file to discover and join the cache. Recommended for production environments.
If you enable multicast, enable it on all nodes. A cluster cannot function properly unless all its nodes use the same form of communication for caching.