我以root用户身份创建/ mysqltmp目录，并赋予它与/ tmp目录（chmod 1777 / mysqltmp）相同的权限。但是当我启动mysql时，服务无法启动，我在日志中收到以下错误：
/usr/sbin/mysqld: Can't create/write to file '/mysqltmp/ib9AeHFf' (Errcode: 13)
140417 9:46:46 InnoDB: Error: unable to create temporary file; errno: 13
140417 9:46:46 [ERROR] Plugin 'InnoDB' init function returned error.
140417 9:46:46 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
140417 9:46:46 [ERROR] Unknown/unsupported storage engine: InnoDB
140417 9:46:46 [ERROR] Aborting
错误13是＆＃34;权限被拒绝＆＃34;。
MySQL服务器版本为5.5.35，操作系统为Ubuntu 12.04.4。