1.root超级用户不能正常启动
由于elasticsearch2.0版本以后不能使用root来启动，所以需要创建一个普通用户来启动。
[root@bogon ~]# groupadd elasticsearch
[root@bogon ~]# useradd elasticsearch -g elasticsearch
[root@bogon ~]# chown -R elasticsearch.elasticsearch /usr/local/elk/elasticsearch-5.2.1
[root@bogon ~]# su - elasticsearch
[elasticsearch@bogon ~]$ cd /usr/local/elk/elasticsearch-5.2.1/bin/
[elasticsearch@bogon bin]$ ./elasticsearch
由普通用户来启动，则可以正常启动服务。
2.ERROR: bootstrap checks failed
max file descriptors [4096] for elasticsearch process likely too low, increase to at least [65536]
max number of threads [1024] for user [lishang] likely too low, increase to at least [2048]
解决：切换到root用户，编辑limits.conf 添加类似如下内容
vi /etc/security/limits.conf
添加如下内容:
* soft nofile 65536
* hard nofile 131072
* soft nproc 2048
* hard nproc 4096
3.max number of threads [1024] for user [lish] likely too low, increase to at least [2048]
解决：切换到root用户，进入limits.d目录下修改配置文件。
vi /etc/security/limits.d/90-nproc.conf
修改如下内容：
* soft nproc 1024
#修改为
* soft nproc 2048
4.max virtual memory areas vm.max_map_count [65530] likely too low, increase to at least [262144]
解决：切换到root用户修改配置sysctl.conf
vi /etc/sysctl.conf
添加下面配置：
vm.max_map_count=655360
并执行命令：
sysctl -p
然后，重新启动elasticsearch，即可启动成功。
