V-Recover: Virtual Machine Recovery When Live Migration Fails

Abstract

Live migration is a critical technology used in cloud infrastructures to transfer running virtual machines (VMs). When live migration fails, as it often does, it is critical that any VMs in transit are not lost. There are two primary live migration techniques – pre-copy and post-copy. Pre-copy transfers a VM's memory to the destination before its virtual CPUs are transferred, whereas post-copy does the reverse. Both pre-copy and post-copy will lose the VM if the source machine fails during migration. Additionally, post-copy can lose the VM if the destination machine or network fail since the VM's memory and execution state are split across the source and destination machines. We present V-Recover, an approach to recover a VM when the source, destination, or network fails during live migration. V-Recover consists of two techniques: (1) a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">forward incremental checkpointing</i> (FIC) mechanism to handle source machine failure during both pre-copy and post-copy, and (2) a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">reverse incremental checkpointing</i> (RIC) mechanism to handle destination or network failure during post-copy. We present the design, implementation, and evaluation of V-Recover in the KVM/QEMU virtualization platform. Our evaluations show that V-Recover effectively recovers a VM upon migration failure with acceptable overheads on migration metrics and application performance.