A backing out capability backs out a component of a computing environment, while maintaining the availability of the computing environment. In particular, a component of the computing environment which is associated with at least a portion of a unit of work is backed out from one version to another version....http://www.google.com.au/patents/US6564376?utm_source=gb-gplus-sharePatent US6564376 - Method, system and program products for operationally backing out components of a cluster through emulation
