Provable Data Possession (PDP) is a technique for ensuring the integrity of data in storage outsourcing. In this paper, the authors address the construction of an efficient PDP scheme for distributed cloud storage to support the scalability of service and data migration, in which they consider the existence of multiple cloud service providers to cooperatively store and maintain the clients' data. They present a Cooperative PDP (CPDP) scheme based on homomorphic verifiable response and hash index hierarchy. They prove the security of their scheme based on multi-prover zero-knowledge proof system, which can satisfy completeness, knowledge soundness, and zero-knowledge properties. In addition, they propose a dynamic audit service for verifying the integrity of untrusted and outsourced storage.