（1）内存不足。
Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x00000000c5330000, 986513408, 0) failed; error='Cannot allocate memory' (errno=12)
#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (mmap) failed to map 986513408 bytes for committing reserved memory.
# An error report file with more information is saved as:解决办法：减少启动程序所需内存，或加大内存，如关闭一些程序。
方法一：扩大虚拟机内存，直接更改虚拟机内存就好了，此方法省略。
方法二：减小所需内存的办法。
进入config，命令： cd config
修改jvm.properties文件,命令： vi jvm.options
可以看到此版本它的默认内存是1G，我们把它设小一点。
保存退出。
（2）不能使用管理员权限启动
[WARN ][o.e.b.ElasticsearchUncaughtExceptionHandler] [] uncaught exception in thread [main]
org.elasticsearch.bootstrap.StartupException: java.lang.RuntimeException: can not run elasticsearch as root
at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:125) ~[elasticsearch-6.2.3.jar:6.2.3]
解决办法：
添加用户，用新用户权限去开启elasticsearch。
命令格式： useradd 用户名 -g 所属组名 -p 密码
groupadd ymq
useradd ymq -g ymq -p ymq
命令格式： chown -R 所属用户 ： 所属用户组名 更改权限的文件路径
chown -R ymq:ymq 路径
chmod -R 777 路径（3）127.0.0.1:9200能访问，ip+端口无法访问
修改es配置文件elasticsearch.yml
加上:network.host: 0.0.0.0
（4）
ERROR: [3] bootstrap checks failed
[1]: max file descriptors [65535] for elasticsearch process is too low, increase to at least [65536]
[2]: max number of threads [3889] for user [myes] is too low, increase to at least [4096]
用root权限修改limits.conf（/etc/seacurity）在第一行增加以下内容：
* soft nofile 65536
* hard nofile 131072
* soft nproc 2048
* hard nproc 4096[3]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]修改配置文件/etc/sysctl.conf在第一行加上下面这句：
vm.max_map_count = 655360
执行命令： sysctl -p
(5)elasticsearch.log (Permission denied)
[es-grass@localhost bin]$ 2018-04-17 09:46:43,322 main ERROR RollingFileManager (/usr/local/elasticsearch-6.0.0/logs/elasticsearch.log) java.io.FileNotFoundException: /usr/local/elasticsearch-6.0.0/logs/elasticsearch.log (Permission denied) java.io.FileNotFoundException: /usr/local/elasticsearch-6.0.0/logs/elasticsearch.log (Permission denied)
at java.io.FileOutputStream.open0(Native Method)
at java.io.FileOutputStream.open(FileOutputStream.java:270)
at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
at java.io.FileOutputStream.<init>(FileOutputStream.java:133)
at org.apache.logging.log4j.core.appender.rolling.RollingFileManager$RollingFileManagerFactory.createManager(RollingFileManager.java:640)
at org.apache.logging.log4j.core.appender.rolling.RollingFileManager$RollingFileManagerFactory.createManager(RollingFileManager.java:608)
at org.apache.logging.log4j.core.appender.AbstractManager.getManager(AbstractManager.java:113)
at org.apache.logging.log4j.core.appender.OutputStreamManager.getManager(OutputStreamManager.java:115)
at org.apache.logging.log4j.core.appender.rolling.RollingFileManager.getFileManager(RollingFileManager.java:188)
at org.apache.logging.log4j.core.appender.RollingFileAppender$Builder.build(RollingFileAppender.java:144)
at org.apache.logging.log4j.core.appender.RollingFileAppender$Builder.build(RollingFileAppender.java:60)
at org.apache.logging.log4j.core.config.plugins.util.PluginBuilder.build(PluginBuilder.java:122)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createPluginObject(AbstractConfiguration.java:958)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:898)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:890)
at org.apache.logging.log4j.core.config.AbstractConfiguration.doConfigure(AbstractConfiguration.java:513)
at org.apache.logging.log4j.core.config.AbstractConfiguration.initialize(AbstractConfiguration.java:237)
at org.apache.logging.log4j.core.config.AbstractConfiguration.start(AbstractConfiguration.java:249)
at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:545)
at org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:261)
at org.elasticsearch.common.logging.LogConfigurator.configure(LogConfigurator.java:164)
at org.elasticsearch.common.logging.LogConfigurator.configure(LogConfigurator.java:120)
at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:290)
at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:130)
at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:121)
at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:69)
at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:134)
at org.elasticsearch.cli.Command.main(Command.java:90)
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:92)
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:85)
将es安装目录及其子目录赋予权限：
sudo chown -R 用户 elasticsearch-6.0.0
sudo chgrp -R 用户组 elasticsearch-6.0.0
