Ensuring Data Consistency over Cms Distributed Computing System

CMS utilizes a distributed infrastructure of computing centers to custodially store data, to provide organized processing resources, and to provide analysis computing resources for users. Integrated over the whole system, even in the first year of data taking, the available disk storage approaches 10 petabytes of space. Maintaining consistency between the data bookkeeping, the data transfer system, and physical storage is an interesting technical and operations challenge. In this paper we will discuss the CMS effort to ensure that data is consistently available at all computing centers. We will discuss the technical tools that monitor the consistency of the catalogs and the physical storage as well as the operations model used to find and solve inconsistencies.