Recently, two very interesting new articles were published on developerWorks. One deals with building geographically dispersed DB2 pureScale clusters, the other has an in-depth look on how to upgrade from DB2 9.7 to the DB2 pureScale feature. In both papers, a detailed description of each step is included.
Geographically dispersed clusters, sometimes referred to as stretch clusters, span multiple locations to be able to continue with processing even when an entire site is down. When all involved sites are up, the processing power of the available sites is used (active/active).