This paper presents an analysis of the cost of Archival Storage. The study is part of a project conducted by The Danish National Archives, The Royal Library and The State and University Library to develop a generic cost model for digital preservation (CMDP). The purposes of the study were to determine the costs of establishing and maintaining a preservation solution destined for long-term preservation of digital materials; and to develop a tool capable of doing this operation. In order to fulfill the purposes, the project employed a combination of own and external experience as well as the OAIS Reference Model as a framework to fully understand and identify the cost critical activities of bit-preservation as described in Archival Storage. We found that the costs of Archival Storage are obviously closely linked to the data volume, but also to the required preservation quality, especially with regard to the required number of copies and the type of storage solution.