elasticsearch 6 在 centos 6 上的安装问题

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]
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，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

对于第二条错误同意需要切换到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

第三条错误需要切换到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。

启动问题

**1、Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x0000000085330000, 2060255232, 0) failed; error=‘Cannot allocate memory‘ (errno=12)**

由于elasticsearch5.0默认分配jvm空间大小为2g，修改jvm空间分配

# vim config/jvm.options  
-Xms2g  
-Xmx2g  
修改为  
-Xms512m  
-Xmx512m  

2、max number of threads [1024] for user [elasticsearch] is too low, increase to at least [2048]修改 /etc/security/limits.d/90-nproc.conf

*          soft    nproc     1024
*          soft    nproc     2048

3、max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]
修改/etc/sysctl.conf配置文件，

cat /etc/sysctl.conf | grep vm.max_map_countvm.max_map_count=262144

如果不存在则添加

echo "vm.max_map_count=262144" >>/etc/sysctl.conf

4、max file descriptors [65535] for elasticsearch process likely too low, increase to at least [65536]
需要执行下面的命令

ulimit -n 65536