Live Migration of Direct-Access Devices
Source: University of Wisconsin
Virtual machine migration greatly aids management by allowing flexible provisioning of resources and decommissioning of hardware for maintenance. However, efforts to improve network performance by granting virtual machines direct access to hardware currently prevent migration. This occurs because the VMM cannot migrate the state of the device, and the source and destination machines may have different network devices, requiring different drivers to run in the migrated virtual machine. In this paper, the authors describe a lightweight software mechanism for migrating virtual machines with direct hardware access. They base the solution on shadow drivers, which efficiently capture and reset the state of a device driver. On the source hardware, the shadow driver continuously monitors the state of the driver and device.