Edit

Cluster States

Overview

An Ignite cluster can be in one of the three states: ACTIVE, ACTIVE_READ_ONLY, and INACTIVE.

When you start a pure in-memory cluster (no persistent data regions) for the first time, the cluster is in the ACTIVE state. When you start a cluster with persistent data regions for the first time, the cluster is INACTIVE.

INACTIVE: All operations are prohibited.

When you change the cluster state from active to INACTIVE (deactivation), the cluster deallocates all memory resources.

Warning

Deactivation deallocates all memory resources, including your application data, on all cluster nodes and disables public cluster API. If you have in-memory caches that are not backed up by a persistent storage (neither native persistent storage nor external storage), you will lose the data and will have to repopulate these caches. The non-persistent system caches are cleared too.

ACTIVE: This is the normal mode of the cluster. You can execute any operation.
ACTIVE_READ_ONLY: The read-only mode. Only read operations are allowed.

Any attempt to create a cache or modify the data in an existing cache results in an IgniteClusterReadOnlyException exception. DDL or DML statements that modify the data are prohibited as well.

Changing Cluster State

You can change the cluster state in multiple ways:

Control script:
```
control.sh --set-state ACTIVE_READ_ONLY
```

REST command:

http://localhost:8080/ignite?cmd=setstate&state=ACTIVE_READ_ONLY

Programmatically:

Ignite ignite = Ignition.start();

ignite.cluster().state(ClusterState.ACTIVE_READ_ONLY);

JMX Bean:
Mbean’s Object Name:
group="Kernal",name=IgniteKernal
Operation Description

clusterState()

Get the current cluster state.

clusterState(String, boolean)

Set the cluster state.

Operation	Description
`clusterState()`	Get the current cluster state.
`clusterState(String, boolean)`	Set the cluster state.

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