VNsnap: Taking snapshots of virtual networked environments with minimal downtime

A virtual networked environment (VNE) consists of virtual machines (VMs) connected by a virtual network. It has been adopted to create “virtual infrastructures” for individual users on a shared cloud computing infrastructure. The ability to take snapshots of an entire VNE — including images of the VMs with their execution, communication and storage states — yields a unique approach to reliability as a snapshot can restore the operation of an entire virtual infrastructure. We present VNsnap, a system that takes distributed snapshots of VNEs. Unlike existing distributed snapshot/checkpointing solutions, VNsnap does not require any modifications to the applications, libraries, or (guest) operating systems running in the VMs. Furthermore, VNsnap incurs only seconds of downtime as much of the snapshot operation takes place concurrently with the VNE's normal operation. We have implemented VNsnap on top of Xen. Our experiments with real-world parallel and distributed applications demonstrate VNsnap's effectiveness and efficiency.