原因：因為太懶在主節點啟動成功之後直接把它copy了一份，導致的這個錯誤，因為伺服器啟動會建立部分檔案。

解決：從tar包重新解壓一個就ok了。

[o.e.d.z.ZenDiscovery     ] [slave1] failed to send join request to master [{master}{BLEigXhhRoOaONB-_LEHlQ}{j9QILYaeTLyZ8_qxWurT8w}{127.0.0.1}{127.0.0.1:9300}{ml.machine_memory=8589934592, ml.max_open_jobs=20, xpack.installed=true, ml.enabled=true}], reason [RemoteTransportException[[master][127.0.0.1:9300][internal:discovery/zen/join]]; nested: IllegalArgumentException[can't add node {slave1}{BLEigXhhRoOaONB-_LEHlQ}{nVq9upw4QL2oaOeVRhrnaw}{127.0.0.1}{127.0.0.1:9301}{ml.machine_memory=8589934592, ml.max_open_jobs=20, xpack.installed=true, ml.enabled=true}, found existing node {master}{BLEigXhhRoOaONB-_LEHlQ}{j9QILYaeTLyZ8_qxWurT8w}{127.0.0.1}{127.0.0.1:9300}{ml.machine_memory=8589934592, xpack.installed=true, ml.max_open_jobs=20, ml.enabled=true} with the same id but is a different node instance]; ]