Cluster
persistence,
caching, and
multicast are configured in the
cluster
node configuration file.
Persistence is enabled for clusters by
default.Persistence
saves
projects and workspaces when the cluster shuts down. All nodes in a cluster must point
to the same persistence directory, which defaults to
ESP_HOME/storage.
Note: If the nodes in a cluster are on
different machines, the persistence folder must be on a shared disk.
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.
Caching and Multicast
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 name and password in
the Cache section of <node-name>.xml.
Managers discover and join an existing cluster cache in one of two
ways:
- 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 the Managers section of its <node-name>.xml 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.