Cloud computing brings new technologies and concepts that favor communication services and data storage. Services like OneDrive, Google Drive and DropBox increase data availability and provide new features as synchronization and collaboration. This article aims to assess the availability and performance of private cloud storage service. A set of models that use a hierarchical strategy is proposed to evaluate both availability and performance through the composition of reliability block diagrams (RBD) and stochastic Petri net (SPN) models. A case study is presented to illustrate the applicability of the proposed models through a cloud storage service hosted on the Eucalyptus platform.