The first step is to install the database that sits at the heart of the cluster. To implement high availability, run an instance of the database on each controller node and use Galera Cluster to provide replication between them. Galera Cluster is a synchronous multi-master database cluster, based on MySQL and the InnoDB storage engine. It is a high-availability service that provides high system uptime, no data loss, and scalability for growth.
You can achieve high availability for the OpenStack database in many different ways, depending on the type of database that you want to use. There are three implementations of Galera Cluster available to you:
In addition to Galera Cluster, you can also achieve high availability through other database options, such as PostgreSQL, which has its own replication system.