Using Capacity Space Methodology for Balancing Server Utilization: Description and Case Studies

Capacity space is a methodology that measures resource utilization at a server and installation level. It predicts potential shortfalls, identifies available resources that can offset shortfalls, guides the rebalancing of existing resources and provides justification for additional capacity. Capacity space is based on life expectancy of a resource, which recombines historical usage data to predict when the resource will exceed a specified limit. The paper describes the capacity space concept and methodology and illustrates its use with two case studies in the IBM Lotus Notes email domain. The first study is a server consolidation that upgraded RS/6000 SP nodes and the second study is a DASD migration to the IBM Enterprise Storage Server on S/390s.