During the in-place upgrade, the original MySQL 5.1 RPM package is uninstalled, and
the new MariaDB 5.5 RPM package is installed instead, but RPM does not take these
operations as an update. Note that the MySQL RPM renames the /etc/my.cnf file to
the /etc/my.cnf.rpmsave file on uninstallation.

After installing MariaDB, type the following command to restore your original
configuration options:

# mv -vi /etc/my.cnf.rpmsave /etc/my.cnf

You can find more information at [link:https://access.redhat.com/articles/723833].

