multiple DBStorage location

[venkat mysql]

I want to have multiple storage location for mysql data all working simultaneously. But when I checked my.cnf file I have only single line stating datadir=/mnt. How can I configure my.cnf file to have multiple DB location. I wanted to achieve this with single mysql installation in a linux machine. If yes is this recommended ?

For example,

I have 50 users and I wanted to have each user separate DBStorage location so that I can umount any user drive and mount it to another machine.

thanks
venkat