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.