MariaDB is a fork of MySQL, which is true open source and community maintained. MariaDB is a binary drop in replacement for MySQL. It includes the XtraDB storage engine as a replacement for InnoDB. Its lead developer is Michael Widenius (also known as "Monty"), the founder of MySQL.
Recently, many popular Linux distributions replaced MySQL with MariaDB as default database server. Fedora version => 19, Archlinux and OpenSuse. Moreover Wikipedia moved to MariaDB and Mozilla also uses MariaDB.
Famous distributions often used in server environments such as Debian and Centos have not replaced MySQL with MariaDB yet, but they'll probaly soon migrate as well.
Why switch to MariaDB
Well, MySQL development has basically stopped, since Oracle acquired MySQL, whereas the MariaDB development is progessing at full speed.
Performance and licensing are the often the most predominant reasons to make a switch from MySQL to MariaDB.
Regarding performance - here is what Wikipedia experienced, when they compared MariaDB to the Facebook fork of MySQL 5.1.
http://blog.wikimedia.org/2013/04/22/wikipedia-adopts-mariadb/ Wikipedia Adopts MariaDB
Many query types were 4-15% faster with MariaDB 5.5.30 under production load, a few were 5% slower, and nothing appeared aberrant beyond those bounds.
Install MariaDB on Debian Wheezy
MariaDB packages are not yet available in official Debian repositories. MariaDB provides repositories for almost every popular os here:
Add the following to your
deb http://ftp.osuosl.org/pub/mariadb/repo/5.5/debian wheezy main
sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 0xcbcb082a1bb943db sudo apt-get update sudo apt-get install mariadb-server-5.5 libmysqlclient18=5.5.30-mariadb1~wheezy
The libmysqlclient18=5.5.30-mariadb1~wheezy is needed as a work-around to this bug.
This should result is something like this...
Reading package lists... Done Building dependency tree Reading state information... Done The following extra packages will be installed: libaio1 libdbd-mysql-perl libdbi-perl libhtml-template-perl libmariadbclient18 libnet-daemon-perl libplrpc-perl mariadb-client-5.5 mariadb-client-core-5.5 mariadb-common mariadb-server-core-5.5 mysql-common psmisc Suggested packages: libipc-sharedcache-perl tinyca mailx mariadb-test The following NEW packages will be installed: libaio1 libdbd-mysql-perl libdbi-perl libhtml-template-perl libmariadbclient18 libmysqlclient18 libnet-daemon-perl libplrpc-perl mariadb-client-5.5 mariadb-client-core-5.5 mariadb-common mariadb-server-5.5 mariadb-server-core-5.5 mysql-common psmisc 0 upgraded, 15 newly installed, 0 to remove and 0 not upgraded. Need to get 32.3 MB of archives. After this operation, 111 MB of additional disk space will be used. Do you want to continue [Y/n]?
You are now ready to use MariaDB.