apache-ignite

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// Licensed to the Apache Software Foundation (ASF) under one or more
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// contributor license agreements.  See the NOTICE file distributed with
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// this work for additional information regarding copyright ownership.
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// The ASF licenses this file to You under the Apache License, Version 2.0
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// (the "License"); you may not use this file except in compliance with
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// the License.  You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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= Cluster States
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:javaFile: {javaCodeDir}/ClusterAPI.java
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== Overview
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An Ignite cluster can be in one of the three states: `ACTIVE`, `ACTIVE_READ_ONLY`, and `INACTIVE`.
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When you start a pure in-memory cluster (no persistent data regions) for the first time, the cluster is in the `ACTIVE` state.
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When you start a cluster with persistent data regions for the first time, the cluster is `INACTIVE`.
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* `INACTIVE`: All operations are prohibited.
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+
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--
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When you change the cluster state from active to `INACTIVE` (deactivation), the cluster deallocates all memory resources.
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include::includes/note-on-deactivation.adoc[]
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--
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* `ACTIVE`: This is the normal mode of the cluster. You can execute any operation.
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* `ACTIVE_READ_ONLY`: The read-only mode. Only read operations are allowed.
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+
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--
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Any attempt to create a cache or modify the data in an existing cache results in an `IgniteClusterReadOnlyException` exception.
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DDL or DML statements that modify the data are prohibited as well.
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--
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== Changing Cluster State
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You can change the cluster state in multiple ways:
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* link:control-script#getting-cluster-state[Control script]:
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[source, shell]
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----
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control.sh --set-state ACTIVE_READ_ONLY
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----
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* link:restapi#change-cluster-state[REST command]:
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+
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--
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[source, url]
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----
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http://localhost:8080/ignite?cmd=setstate&state=ACTIVE_READ_ONLY
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----
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--
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* Programmatically:
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[tabs]
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--
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tab:Java[]
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[source, java]
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----
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include::{javaFile}[tags=change-state, indent=0]
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----
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tab:C#/.NET[]
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tab:C++[]
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--
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* JMX Bean:
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--
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Mbean's Object Name: ::
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----
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group="Kernal",name=IgniteKernal
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----
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[cols="1,4",opts="header"]
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|===
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|Operation | Description
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| `clusterState()` | Get the current cluster state.
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| `clusterState(String, boolean)` | Set the cluster state.
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|===
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--
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