FVM: FPGA-assisted Virtual Device Emulation for Fast, Scalable, and Flexible Storage Virtualization

Emerging big-data workloads with massive I/O processing require fast, scalable, and flexible storage virtualization support. Hardware-assisted virtualization can achieve reasonable performance for fast storage devices, but it comes at the expense of limited functionalities in a virtualized environment (e.g., migration, replication, caching). To restore the VM features with minimal performance degradation, recent advances propose to implement a new software-based virtualization layer by dedicating computing cores to virtual device emulation. However, due to the dedication of expensive general-purpose cores and the nature of host-driven storage device management, the proposed schemes raise the critical performance and scalability issues with the increasing number and performance of storage devices per server.In this paper, we propose FVM, a new hardware-assisted storage virtualization mechanism to achieve high performance and scalability while maintaining the flexibility to support various VM features. The key idea is to implement (1) a storage virtualization layer on an FPGA card (FVM-engine) decoupled from the host resources and (2) a device-control method to have the card directly manage the physical storage devices. In this way, a server equipped with FVM-engine can save the invaluable host-side resources (i.e., CPU, memory bandwidth) from virtual and physical device management and utilize the decoupled FPGA resources for virtual device emulation. Our FVM-engine prototype outperforms existing storage virtualization schemes while maintaining the same flexibility and programmability as software implementations.