1 About High Availability Clustering
This chapter describes how to set up and configure the Pacemaker and Corosync technologies to create a high availability (HA) cluster that delivers continuous access to services that are running across multiple nodes.
High availability services in Oracle Linux consist of several open source packages, including the Corosync and Pacemaker features. These tools enable you to achieve high availability for applications and services that are running on Oracle Linux. You can download Corosync, Pacemaker, and any dependencies and related packages from the Unbreakable Linux Network (ULN) at https://linux.oracle.com or the Oracle Linux yum server at https://yum.oracle.com.
Corosync is an open source cluster engine that includes an API to implement several high availability features, including an availability manager that can restart a process when it fails, a configuration and statistics database, and a quorum system that can notify applications when quorum is achieved or lost.
Corosync is installed with Pacemaker, which is an open source high availability cluster resource manager that's responsible for managing the life cycle of software that's deployed on a cluster. Pacemaker also provides high availability services, which are achieved by detecting and recovering from node and resource-level failures by using the API that's provided by the cluster engine.
Pacemaker also ships with the Pacemaker Command Shell
(pcs). You can use the pcs
command to access and configure the cluster and its resources. The
pcs daemon runs as a service on each node in
the cluster, making it possible to synchronize configuration
changes across all of the nodes in the cluster.
Oracle provides support for Corosync and Pacemaker that's used for an active-passive 2-node (1:1) cluster configuration on Oracle Linux 8. Note that support for clustering services doesn't imply support for Oracle products that are clustered by using these services.
Oracle also provides Oracle Clusterware for high availability clustering with Oracle Database. You can find more information at https://www.oracle.com/database/technologies/rac/clusterware.html.