部署elasticsearch需要调整的系统参数

在部署elasticsearch启动的过程中失败了，具体报错如下:

ERROR: [2] bootstrap checks failed
[1]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]
[2]: the default discovery settings are unsuitable for production use; at least one of [discovery.seed_hosts, discovery.seed_providers, cluster.initial_master_nodes] must be configured
ERROR: Elasticsearch did not exit normally - check the logs at /usr/share/elasticsearch/logs/docker-cluster.log

ERROR: [1] bootstrap checks failed. You must address the points described in the following [1] lines before starting Elasticsearch.
bootstrap check failure [1] of [1]: max file descriptors [4096] for elasticsearch process is too low, increase to at least [65535]
ERROR: Elasticsearch did not exit normally - check the logs at /data1/elasticsearch/logs/starces.log

解决方法:
报错的意思是ElasticSearch拥有的内存太小，至少需要262144。查看命令sysctl -a|grep vm.max_map_count可以看到到vm.max_map_count = 65530，需要增加这个值。临时生效的方法：sysctl -w vm.max_map_count=262144。如果需要永久生效，需要在/etc/sysctl.conf文件下添加一行：vm.max_map_count=262144并重启，即可解决。重启命令如下:

sysctl -p

最大线程个数太低。修改配置文件/etc/security/limits.conf

* soft nofile 65536
* hard nofile 65536
* soft nproc 4096
* hard nproc 4096

–查看当前系统配置文件ulimit的全局配置

ulimit -a

如果未进行具体设置的话，会使用默认配置，如下查看

grep '^*' /etc/security/limits.conf