From Fedora Project Wiki

No data upgrade needed if replacing the same version
When replacing MySQL with MariaDB that are of the same minor version (e.g. from mysql-5.5.x to mariadb-5.5.x) we don't have to do upgrade data.
Data backup
Before upgrading from MySQL to MariaDB, we recommend to backup important data for the case something gets wrong.

Testing Yum repository for Fedora 18

We've prepared a testing Yum repository with RPMs for Fedora 18, which correspond with packages that are being prepared for Fedora 19. The repository is located in and to use it, just copy it to /etc/yum.repos.d/.

# wget -o /etc/yum.repos.d/mariadb-testday.repo
Testing repository disabled by default
This testing repository is disabled by default, which means it won't be used unless explicitly enabled by --enablerepo Yum argument.

Proceeding the upgrade (replace MySQL packages by MariaDB packages)

Except --enablerepo=mariadb-testday we also use --disablerepo=* in order to not update other packages during test. You can let this argument out if you want update all packages.

The replacement of already installed MySQL packages with MariaDB alternative will be proceeded as follows:

yum update --disablerepo=* --enablerepo=mariadb-testday

For installing MariaDB server package use:

yum install --disablerepo=* --enablerepo=mariadb-testday mariadb-server

Going back to backed-up data if something gets wrong

In case something gets wrong, you can get back to backed-up data.

Expected results

Now you should have installed only MariaDB packages, while all MySQL packages should have been removed. You can check that using:

$ rpm -qa | grep -e '^mysql' -e '^mariadb'