IBM HACMP

• Standby configurations
  Standby configurations are the traditional redundant hardware configurations where one or more standby nodes stand idle, waiting for a server node to leave the cluster.
• Takeover configurations
  In the takeover configurations, all cluster nodes do useful work, processing part of the cluster's workload. There are no standby nodes. Takeover configurations use hardware resources more efficiently than standby configurations since there is no idle processor. Performance can degrade after node detachment, however, since the load on remaining nodes increases.
• Refer to http://pic.dhe.ibm.com/infocenter/aix/v6r1/index.jsp?topic=%2Fcom.ibm.aix.hacmp.concepts%2Fha_concepts_hacmp_cluster_config.htm.
• Standby uses a primary/backup way.