DualVisor: Redundant Hypervisor Execution for Achieving Hardware Error Resilience in Datacenters

Virtualization technology as the foundation of cloud computing provides many benefits in cost, security, and management, but all of them rely on the reliability of the underlying virtualization software - the hypervisor (or virtual machine monitor). Cloud data centers are built upon 10Ks to 100Ks commodity servers. Hardware errors in these large scale computer systems are not rare events. When hardware errors occur during the hypervisor execution, they may cause failures or data corruptions in co-located VMs, undermining the whole system reliability. In this paper, we propose DualVisor, that uses a software redundancy based fault tolerance technique to protect the hypervisor from hardware errors. DualVisor replicates hypervisor executions and data structures for error detection and recovery. In this work, we first study the need for a hardware error-resilient hypervisor. Then, we discuss the design considerations in detail. We implement a prototype in the hypervisor to demonstrate the feasibility and evaluate the performance overhead. Our preliminary results show that the performance overhead of DualVisor is fairly small (less than 6%) for tested applications.