With growing scientific communities with large amounts of different data to be stored, mixed storage systems based on disk and tape devices are widely used. These storage systems commonly offer proprietary interfaces with non-uniform feature sets. To ensure data consistency most storage systems rely on the calculation of checksums attached to the stored data objects. In this document we propose a service architecture that is capable of providing a uniform interface to different underlying storage systems to simplify the access to these checksums as well as to other i.e. domain specific metadata records.