今天在做关于xtrabackup的实验过程中mysql起不来了，经过检查发现是权限设置的问题。由此想到在日常的工作中会出现mysql启动不了的问题，这里建个帖子，把遇到的问题都收集过来，便于查阅。
1、 权限未进行配置
以下是日志信息：
150327 13:06:54mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/data
150327 13:06:55[Note] Plugin ‘FEDERATED‘ is disabled.
15032713:06:55 InnoDB: Started; log sequencenumber 0 343564
150327 13:06:55[ERROR] Event Scheduler: Failed to open table mysql.event
150327 13:06:55[ERROR] Event Scheduler: Error while loading from disk.
150327 13:06:55[Note] Event Scheduler: Purging the queue. 0 events
150327 13:06:55[ERROR] Aborting
15032713:06:55 InnoDB: Starting shutdown...
15032713:06:56 InnoDB: Shutdown completed; logsequence number 0 343564
150327 13:06:56[Note] /usr/local/mysql/bin/mysqld: Shutdown complete
解决方法：
chown mysql:mysql-R /usr/local/mysql/data
chmod 660 -R/usr/local/mysql/data
原文：http://881955.blog.51cto.com/871955/1642069