I recently started to put ownCloud on my Pi and got it working but then decided to move the ownCloud storage and MySQL database to a external hard drive. Mainly to save the flash card from burning out since I was going to be pushing a lot of files around. I found multiple methods of moving the MySQL database online in only a few steps but I can never got the service to start. Below is the errors from the logs. MySQL shows that its a permission issue but even setting up the owner as "chown -R mysql:mysql /media/ownCloud/ownCloudData/mysql" permission is still a issue. I did think AppArmour was to blame but its doesn't look to be installed by default on Raspbian. Any ideas on what I'm missing?

my.cnf
datadir = /media/ownCloud/ownCloudData/mysql
innodb_data_home_dir = /media/ownCloud/ownCloudData/mysql

MySQL error.log
innodb: operating system error number 13 in a file operation
innodb: error means mysqld does not have the access rights to the directory
innodb: File name /media/ownCloud/ownCloudData/mysql/ibdata1
innodb: file operation call: 'create'

syslog
raspberrypi /etc/init.d/mysql[3031]: 0 processes alive and '/usr/bin/mysqladmin --defaults-file=/etc/mysql/debian.cnf ping' resulted in
raspberrypi /etc/init.d/mysql[3031]: #007/usr/bin/mysqladmin: connect to server at 'localhost' failed
raspberrypi /etc/init.d/mysql[3031]: error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)'
raspberrypi /etc/init.d/mysql[3031]: Check that mysqld is running and that the socket: '/var/run/mysqld/mysqld.sock' exists!

What about the permissions?

I have made sure the owner is MySQL using chown and it is granted r/w.

if you don't use the standard location for the socketfile (/tmp/mysql.sock) you should set "socket=path-to-socketfile" explicitly in your my.cnf both in mysqld AND in client sections, thats where mysqladmin is looking at when connecting from localhost. Otherwise you should provide a --socket=... when invoking a client program. You can find the location in the process string from "ps -ef | grep mysql", if it is set differently.