pid及socket文件丢失，数据库无法启动问题

日志如下

151119 19:11:45 mysqld_safe mysqld from pid file /data/mysql/miles.pid ended151119 19:14:56 mysqld_safe Starting mysqld daemon with databases from /data/mysql151119 19:14:56 [Note] /usr/local/mysql/bin/mysqld (mysqld 5.5.46) starting as process 4373 ...151119 19:14:56 InnoDB: The InnoDB memory heap is disabled151119 19:14:56 InnoDB: Mutexes and rw_locks use GCC atomic builtins151119 19:14:56 InnoDB: Compressed tables use zlib 1.2.3151119 19:14:56 InnoDB: Initializing buffer pool, size = 128.0M151119 19:14:56 InnoDB: Completed initialization of buffer poolInnoDB: Error: log file ./ib_logfile0 is of different size 0 50331648 bytesInnoDB: than specified in the .cnf file 0 5242880 bytes!'151119 19:14:56 [ERROR] Plugin 'InnoDB' init function returned error.''151119 19:14:56 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.''151119 19:14:56 [ERROR] Unknown/unsupported storage engine: InnoDB''151119 19:14:56 [ERROR] Aborting'

原因：主要是没有正常关闭mysqld服务的情况下，对数据库参数进行改变导致的。因此重启后的服务器不支持InnoDB引擎。
处理方法：删除目录下的ib_logfile0和ib_logfile1文件。