mysql启动问题

/usr/local/mysql/bin/mysqld: Can't find file: './mysql/plugin.frm' (errno: 13 - Permission denied)
-- ::  [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
-- ::  [Note] InnoDB: Using atomics to ref count buffer pool pages
-- ::  [Note] InnoDB: The InnoDB memory heap is disabled
-- ::  [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
-- ::  [Note] InnoDB: Memory barrier is not used
-- ::  [Note] InnoDB: Compressed tables use zlib 1.2.
-- ::  [Note] InnoDB: Using CPU crc32 instructions
-- ::  [Note] InnoDB: Initializing buffer pool, size = 128.0M
InnoDB: mmap( bytes) failed; errno
-- ::  [ERROR] InnoDB: Cannot allocate memory for the buffer pool
-- ::  [ERROR] Plugin 'InnoDB' init function returned error.

Can't find file: './mysql/plugin.frm' (errno: 13 - Permission denied)
主要是权限不足引起的，进入mysql数据库

cd /usr/local/mysql/data/mysql

添加权限

chown mysql *
chgrp mysql *
chmod ug+rwx *

重新启动数据库服务。