Peer-to-Peer (P2P) systems are widely used for data sharing applications in an autonomous and decentralized mode. P2P systems are suitable for largescale distributed environments in which nodes can share resources other than data such as computing power, memory and network bandwidth. Some of important parameters that affect the performance of P2P systems are peer availability, data availability, network overhead, overlay structure, churn rate, and data access time. In this paper a self organized replica overlay scheme "Improved Hierarchical Quorum Consensus" (IHQC) for P2P systems is proposed. This scheme organizes replicas in a Self Organized Hierarchical Logical Structure (SOHLS) that has special properties.