KVM Forum 2024

Live Updates are an increasingly successful way to update the host kernel and userland on a KVM host with very little downtime, and without the need for Live Migration. It works by leaving VM state in memory and switching to a new kernel via kexec without a full power cycle. For our cloud computing business @ Akamai, this is a game changer. Capacity constraints are a driving motivator for us to use live updates, particularly with the way we operate at the edge. We operate a product named Akamai Cloud Computing (formerly www.linode.com). Oftentimes, live migration is very not an option due to those capacity constraints. In working with the recently merged CPR (Checkpoint Restart) feature, we are putting this new QEMU functionality to good use. We are actively productionizing the use of Live Updates and in this talk we describe some of the challenges we went through to make Live Updates work. We're hoping that tales from a cloud provider will motivate more companies to get engaged with this powerful support from QEMU so that Live Updates can become a routine operation in the cloud.