Mysql Infobright启动错误：致命错误：

这是安装日志

11:30:18
11:30:18 Installing infobright 4.0.7-0 (i686)
11:30:18 The installer will generate /tmp/ib4.0.7-0-install.log install trace log.
11:30:18 [step: pre (4.0.7-0, 1=1)]
11:30:18 build type: static
11:30:23 [step: post (4.0.7-0), 1=1]
11:30:23 Install with RPM_INSTALL_PREFIX=/usr/local, current prefix=/usr/local/infobright, prefix_actual=/usr/local/infobright-4.0.7-i686
11:30:23 upgrade=
11:30:23 Config file /etc/my-ib.cnf created
11:30:23 sed -e 's+@BH_PORT@+5029+' -e 's+@BH_BASEDIR@+/usr/local/infobright-4.0.7-i686+' -e 's+@BH_SOCK@+/tmp/mysql-ib.sock+' -e 's+@BH_DATADIR@+/usr/local/infobright-4.0.7-i686/data+' < /usr/local/infobright-4.0.7-i686/support-files/my-ib-master.cnf.in > /etc/my-ib-master.cnf
11:30:23 sed -e 's+@BH_PORT@+5029+' -e 's+@BH_BASEDIR@+/usr/local/infobright-4.0.7-i686+' -e 's+@BH_SOCK@+/tmp/mysql-ib.sock+' -e 's+@BH_DATADIR@+/usr/local/infobright-4.0.7-i686/data+' < /usr/local/infobright-4.0.7-i686/support-files/my-ib-slave.cnf.in > /etc/my-ib-slave.cnf
11:30:23 Creating/Updating datadir and cachedir
11:30:23 Creating user mysql and group mysql
groupadd: group 'mysql' already exists
useradd: user 'mysql' already exists
usermod: no changes
11:30:23 create_daemon>
11:30:23 cmd_sed=sed -e 's+@BH_CONF@+/etc/my-ib.cnf+'    -e 's+@BH_USER@+mysql+' < /usr/local/infobright/support-files/mysql.server> /etc/init.d/mysqld-ib
11:30:23 <create_daemon done.
11:30:23 Infobright server installed into folder /usr/local/infobright
11:30:23 Installation log file /tmp/ib4.0.7-0-install.log
Skipping confman during installation..
11:30:23 --------------------------------------
11:30:23 To activate infobright server, please run ./postconfig.sh script from /usr/local/infobright-4.0.7-i686.
11:30:23 Example command: cd /usr/local/infobright-4.0.7-i686; ./postconfig.sh

---

我看到一堆日志消息，我没有看到任何问题。这里有什么问题..我如何解决它？

11:45:00[ERROR]致命错误：无法更改为以用户“mysql”身份运行；请检查用户是否存在。您是否检查过mysql用户是否存在，以及初始化Infobright的用户是否可以更改为它？当然，我尝试以root用户身份运行Infobright。
140613 11:34:03 mysqld_safe Starting mysqld daemon with databases from /usr/local/infobright-4.0.7-i686/data
140613 11:34:03 [Warning] options --log-slow-admin-statements, --log-queries-not-using-indexes and --log-slow-slave-statements have no effect if --log_slow_queries is not set
140613 11:34:03 [ERROR] Fatal error: Can't change to run as user 'mysql' ; Please check that the user exists!

140613 11:34:03 [ERROR] Aborting

140613 11:34:03 [Note] /usr/local/infobright-4.0.7-i686/bin/mysqld: Shutdown complete

140613 11:34:03 mysqld_safe mysqld from pid file /usr/local/infobright-4.0.7-i686/data/IA-VM.pid ended
140613 11:45:00 mysqld_safe Starting mysqld daemon with databases from /usr/local/infobright-4.0.7-i686/data
140613 11:45:00 [Warning] options --log-slow-admin-statements, --log-queries-not-using-indexes and --log-slow-slave-statements have no effect if --log_slow_queries is not set
140613 11:45:00 [ERROR] Fatal error: Can't change to run as user 'mysql' ; Please check that the user exists!

140613 11:45:00 [ERROR] Aborting

140613 11:45:00 [Note] /usr/local/infobright-4.0.7-i686/bin/mysqld: Shutdown complete

140613 11:45:00 mysqld_safe mysqld from pid file /usr/local/infobright-4.0.7-i686/data/IA-VM.pid ended