Abstract: Asymmetric cluster storage systems are becoming a focus due to the high I/O performance, high scalability, easy management, etc.Storage virtualization is one of the key technologies to improve the scalability and manageability of cluster storage systems.From the perspective of building an intelligent storage router, this paper presented a block virtualization method with layered mapping, by which central management and distributed mapping for resource were implemented.This approach supports physical storage resources to be joined in storage system dynamically, and enables good scalability and manageability for the whole storage system.