有時，我們的ES集群小，或者是測試時，只啟動一個es時，我們需要將分片數設小，副本數設為0。要不然集群一直是yellow狀態。
elasticsearch.yml 里設置index.number_of_shards參數已經廢棄，會報錯：
[2018-03-26T13:34:41,435][WARN ][o.e.c.s.SettingsModule ] [node-1] ************************************************************************************* Found index level settings on node level configuration. Since elasticsearch 5.x index level settings can NOT be set on the nodes configuration like the elasticsearch.yaml, in system properties or command line arguments.In order to upgrade all indices the settings must be updated via the /${index}/_settings API. Unless all settings are dynamic all indices must be closed in order to apply the upgradeIndices created in the future should use index templates to set default values. Please ensure all required values are updated on all indices by executing: curl -XPUT 'http://localhost:9200/_all/_settings?preserve_existing=true' -d '{ "index.number_of_replicas" : "0" }' ************************************************************************************* [2018-03-26T13:34:41,438][ERROR][o.e.b.Bootstrap ] Exception java.lang.IllegalArgumentException: node settings must not contain any index level settings at org.elasticsearch.common.settings.SettingsModule.<init>(SettingsModule.java:128) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.node.Node.<init>(Node.java:331) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.node.Node.<init>(Node.java:246) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Bootstrap$5.<init>(Bootstrap.java:213) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:213) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:323) [elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:121) [elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:112) [elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:86) [elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:124) [elasticsearch-cli-6.2.2.jar:6.2.2] at org.elasticsearch.cli.Command.main(Command.java:90) [elasticsearch-cli-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:92) [elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:85) [elasticsearch-6.2.2.jar:6.2.2] [2018-03-26T13:34:41,443][WARN ][o.e.b.ElasticsearchUncaughtExceptionHandler] [node-1] uncaught exception in thread [main] org.elasticsearch.bootstrap.StartupException: java.lang.IllegalArgumentException: node settings must not contain any index level settings at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:125) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:112) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:86) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:124) ~[elasticsearch-cli-6.2.2.jar:6.2.2] at org.elasticsearch.cli.Command.main(Command.java:90) ~[elasticsearch-cli-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:92) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:85) ~[elasticsearch-6.2.2.jar:6.2.2] Caused by: java.lang.IllegalArgumentException: node settings must not contain any index level settings at org.elasticsearch.common.settings.SettingsModule.<init>(SettingsModule.java:128) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.node.Node.<init>(Node.java:331) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.node.Node.<init>(Node.java:246) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Bootstrap$5.<init>(Bootstrap.java:213) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:213) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:323) ~[elasticsearch-6.2.2.jar:6.2.2] at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:121) ~[elasticsearch-6.2.2.jar:6.2.2] ... 6 more所以我們根據提示，配置文件去掉這個參數，啟動起來后，通過API設置：
[elklog@iZ2ze16gjdevwfzy53xejgZ logs]$ curl -XPUT 'http://localhost:9200/_all/_settings?preserve_existing=true' -d '{ > "index.number_of_replicas" : "0" > }' {"error":"Content-Type header [application/x-www-form-urlencoded] is not supported","status":406}[elklog@iZ2ze16gjdevwfzy53xejgZ logs]$ 看來還需要設置http頭信息：
[elklog@iZ2ze16gjdevwfzy53xejgZ logs]$ curl -H "Content-Type: application/json" -XPUT 'http://localhost:9200/_all/_settings?preserve_existing=true' -d '{ > "index.number_of_replicas" : "0" > }' {"acknowledged":true}分片設置同理：
curl -H "Content-Type: application/json" -XPUT 'http://localhost:9200/_all/_settings?preserve_existing=true' -d '{ "index.number_of_shards" : "1" }'