WHOBBS: An Object-Based Distributed Hybrid Storage Providing Block Storage for Virtual Machines

Because of its high IO performance, Solid State Drives (SSDs) are playing an important role in cloud storage services. However, its ten times price of Hard Disk Drives (HDDs) makes it unaffordable for most companies to replace all traditional HDD storage with high performance SSD storage. Hybrid storage becomes a trade-off solution between relatively high performance and acceptable cost. In this paper, we propose an object-based hybrid storage system called WHOBBS to provide high-performance block storage for virtual machines in IaaS. WHOBBS introduces logical storage pools to manage different types of storage devices and splits VM disk images into the objects residing in different storage pools. WHOBBS will optimize the IO performance of the system by dynamic object migration, according to the periodically analyzed access patterns of all objects and the determined global object placement strategy. We evaluate WHOBBS under several benchmarks and demonstrate its efficiency and effectiveness.