Corosync Cluster Engine

The Corosync Cluster Engine is an open source implementation of the Totem Single Ring Ordering and Membership protocol. It was originally derived from the OpenAIS project and licensed under the new BSD License. The mission of the Corosync effort is to develop, release, and support a community-defined, open source cluster.
Features.
The Corosync Cluster Engine is a group communication system with additional features for implementing high availability within applications.
The project provides four C API features:
The software is designed to operate on UDP/IP and InfiniBand networks.
Architecture.
The software is composed of an executive binary which uses a client-server communication model between libraries and service engines. Loadable modules, called service engines, are loaded into the Corosync Cluster Engine and use the services provided by the Corosync Service Engine internal API.
The services provided by the Corosync Service Engine internal API are:
Additionally Corosync provides several default service engines that are used via C APIs:
History.
The project was formally announced in July 2008 via a conference paper at the Ottawa Linux Symposium. The source code of OpenAIS was refactored such that the core infrastructure components were placed into Corosync and the SA Forum APIs were kept in OpenAIS.
In the second version of corosync, published in 2012, quorum subsystem was changed and integrated into the daemon. This version is available since Fedora 17 and RHEL7.