The Red Hat OpenStack Platform director uses a Controller node cluster to provide high availability services to your OpenStack Platform environment. The director installs a duplicate set of components on each Controller node and manages them together as a single service. This type of cluster configuration provides a fallback in the event of operational failures on a single Controller node; this provides OpenStack users with a certain degree of continuous operation.
The OpenStack Platform director uses some key pieces of software to manage components on the Controller node:
Pacemaker - Pacemaker is a cluster resource manager. Pacemaker manages and monitors the availability of OpenStack components across all nodes in the cluster.
HAProxy - Provides load balancing and proxy services to the cluster.
Galera - Replicates the Red Hat OpenStack Platform database across the cluster.
Memcached - Provides database caching.
Red Hat OpenStack Platform director automatically configures the bulk of high availability on Controller nodes. However, the nodes require some manual configuration to enable fencing and power management controls. This guide includes these instructions.