Win 7 x64, MariaDB 5.5.31 x64, MySQL 5.5.31 x64

User, that runs mysqld.exe should be able to access fiiles under the directory . MariaDB runs under NetworkService, by default, as it is a (relatively) weak predefined account, for security reasons. MySQL traditionally ran as LocalSystem, the most powerful account (comparable to Unix "root" ), but I think they have changed it with "universal" installer, and run, just like we, as NetworkService.

The above means, that if you use symlink to some other directory, you should make sure NetworkService, or whatever user is running mysqld.exe, has full access to the directory.

You can grant full access to directory and files in this directory to NetworkService account like this

icacls "C:\path\to\directory" /grant NetworkService:(OI)(CI)F

as described here http://stackoverflow.com/questions/2928738/how-to-grant-permission-to-users-for-a-directory-using-command-line-in-windows

I assume this clarifies the issue. I'm closing this as "Not a Bug". But of course, feel free to reopen, if you still think that MariaDB is doing something wrong.

Yeah - I can accept that as closed
Might be worth updating the documentation to explain that
Even when I rehomed the Data drive to the same location, it would explain why I couldn't access the database
Good to know
Cheers