Live Migration Ate My VM: Recovering a Virtual Machine after Failure of Post-Copy Live Migration

Post-copy is one of the two key techniques (besides pre-copy) for live migration of virtual machines in data centers. Post-copy provides deterministic total migration time and low downtime for write-intensive VMs. However, if post-copy migration fails for any reason, the migrating VM is lost because the VM's latest consistent state is split between the source and destination nodes during migration. In this paper, we present PostCopyFT, a new approach to recover a VM after a destination or network failure during post-copy live migration using an efficient reverse incremental checkpointing mechanism. We have implemented and evaluated our approach in the KVM/QEMU platform. Our experimental results show that the total migration time of post-copy remains unchanged while maintaining low failover time, downtime, and application performance overhead.