环境：
CentOS6.5
Cassnadra3.10
问题：Cassandra WARN级别日志
WARN [main] 2018-04-11 13:32:51,296 CLibrary.java:178 - Unable to lock JVM memory (ENOMEM). This can result in part of the JVM being swapped out, especially with mmapped I/O enabled. Increase RLIMIT_MEMLOCK or run Cassandra as root.
WARN [main] 2018-04-11 13:32:51,296 CLibrary.java:178 - Unable to lock JVM memory (ENOMEM). This can result in part of the JVM being swapped out, especially with mmapped I/O enabled. Increase RLIMIT_MEMLOCK or run Cassandra as root.
我的Cassandra是以cassandra用户运行的，不是root，按照WARN提示将RLIMIT_MEMLOCK增大。
问题解决：
步骤一: 修改limits.conf
vi /etc/security/limits.conf
写入
cassandra - memlock unlimited cassandra - nofile 100000 cassandra - nproc 32768 cassandra - as unlimited
其中，cassandra是我运行cassandra服务的用户名。
步骤二： 修改90-nproc.conf
vi /etc/security/limits.d/90-nproc.conf写入
cassandra - nproc 32768步骤三： 修改 sysctl.conf
vi /etc/sysctl.conf
写入
# Increase RLIMIT_MEMLOCK for cassandra vm.max_map_count = 1048575
步骤四：让配置生效
sysctl -p
步骤五：重启cassandra服务
步骤六：查看修改后的参数已经生效
cat /proc/cassandra_pid/limits其中，cassandra_pid为cassandra服务的进程id
其他操作系统配置参考官方文档：https://docs.datastax.com/en/dse-trblshoot/doc/troubleshooting/insufficientResources.html