For performance reasons, separating DBs to Multiple hard disks can be beneficial
In Linux, when you want to include a directory for a database, you add a symbolic link ( Using the ln -s targetdir command), in Windows, there are no symbolic links, and Windows Shortcuts ( Via right click create shortcut ) don’t work
The truth is, MySQL enables Symbolic Links in Windows by default, but you have to do it the MySQL way
MySQL is a file based database engine, you should be able to see a folder for every database run by your database engine, Now to move one of those DBs to a different directory or hard drive, you just copy it to the new destination and create a file db_name.sym then, within that plain text file, you can add D:datadb_name where D:datadb_name is the folder containing the MySQL files.
You should be good to go if you have moved the directory of the database to d:data, but if you copied it, the copy in the original MySQL data directory will be used
You are done, Now you should experience the extra performance of combining disks, the closest it gets without RAID and a reformat, surely this is assuming the DBs are used evenly
But there are other reasons why you may want to do this, one of which is, when you want to compile all user data in a directory, So DBs that person creates using your server management software puts all that person’s software in one place so that when he or she requests a backup, you know what to send him/her
Enjoy