设置max_connections无效 在/etc/mysql/my.cnf中设置max_connections=512进入Mysql查看发现还是214mysql> show global variables like '%max_connecti%'; +-----------------+-------+ | Variable_name | Value | +-----------------+-------+ | max_connections | 214 | +-----------------+-------+ 1 row in set (0.01 sec)google了一番后，说是跟open_files_limit有关,每个connect都会打开几个文件,查了下open_files_limit为1024。mysql> show global variables like '%open_files_limit%'; +------------------+-------+ | Variable_name | Value | +------------------+-------+ | open_files_limit | 1024 | +------------------+-------+ 1 row in set (0.00 sec)在/etc/mysql/my.cnf中加上open_files_limit = 4096重启mysql后查看mysql> show global variables like '%max_connecti%'; +-----------------+-------+ | Variable_name | Value | +-----------------+-------+ | max_connections | 512 | +-----------------+-------+ 1 row in set (0.01 sec)mysql> show global variables like '%open_files_limit%'; +------------------+-------+ | Variable_name | Value | +------------------+-------+ | open_files_limit | 4096 | +------------------+-------+ 1 row in set (0.00 sec)open_files_limit最大值也是有限制的，设置太大也会变成默认1024，可以在/etc/security/limits.conf加上并重启系统* soft nofile 65536 * hard nofile 65536还有就是启动mysql的service加上LimitNOFILE=65535并重启mysql，这样可以解除open file的限制，LimitNOFILE=65535