Cluster Resource Manager
Pacemaker is an open source, high availability resource manager suitable for both small and large clusters.
"The definitive open-source high-availability stack for the Linux platform builds upon the Pacemaker cluster resource manager." -- LINUX Journal, "Ahead of the Pack: the Pacemaker High-Availability Stack"
Pacemaker has been around since 2004 and is a collaborative effort by the ClusterLabs community, including full-time developers with Red Hat and SuSE.
Pacemaker ships with most modern Linux distributions and has been deployed in many critical environments including Deutsche Flugsicherung GmbH (DFS) which uses Pacemaker to ensure its air traffic control systems are always available.
Andrew Beekhof was Pacemaker's original author and long-time project lead. The current project lead is Ken Gaillot.