• MariaDB:

  Configuring MariaDB for high availability requires configuring MariaDB for replication. For more information, see https://mariadb.com/kb/en/mariadb/setting-up-replication/.

• MySQL:

  Configuring MySQL for high availability requires configuring MySQL for replication. Replication configuration depends on which version of MySQL you are using. For version 5.1, http://dev.mysql.com/doc/refman/5.1/en/replication-howto.html provides an introduction.

  MySQL GTID-based replication is not supported.

• PostgreSQL:

  PostgreSQL has extensive documentation on high availability, especially for versions 9.0 and higher. For information about options available for version 9.1, see http://www.postgresql.org/docs/9.1/static/high-availability.html.

• Oracle:

  Oracle supports a wide variety of free and paid upgrades to their database technology that support increased availability guarantees, such as their Maximum Availability Architecture (MAA) recommendations. For more information, see http://www.oracle.com/technetwork/database/features/availability/oracle-database-maa-best-practices-155386.html.

DRBD is an open-source Linux-based disk replication mechanism that works at the individual write level to replicate writes on multiple machines. Although not directly supported by major database vendors (at the time of writing of this document), it provides a way to inexpensively configure redundant distributed disk for disk-consistent databases (such as MySQL, PostgreSQL, and Oracle). For information, see http://drbd.linbit.com.