Are MySQL databases always stored in /var on CentOS?
Solution 1:
In your case /var is stored on /dev/sda3 as a subdirectory of /.
The default datadir for MySQL is /var/lib/mysql and as long as you do not change the configuration, the database files are stored in this directory.
Solution 2:
In *nix, if a directory is not a separate mount then it is part of its parent mount. In this case, /var is considered part of /.