Prebaked µVMs: Scalable, Instant VM Startup for IaaS Clouds

IaaS clouds promise instantaneously available resources to elastic applications. In practice, however, virtual machine (VM) start up times are in the order of several minutes, or at best, several tens of seconds, negatively impacting the elasticity of applications like Web servers that need to scale out to handle dynamically increasing load. VM start up time is strongly influenced by booting the VM's operating system. In this work, we propose using so-called prebaked uVMs to speed up VM start up. Uvms are snapshots of minimal VMs that can be quickly resumed and then configured to application needs by hot-plugging resources. To serve uVMs, we extend our VM boot cache service, Squirrel, allowing to store uVMs for large numbers of VM images on the hosts of a data center. Our experiments show that uVMs can start up in less than one second on a standard file system. Using 1000+ VM images from a production cloud, we show that the respective uVMs can be stored in a compressed and deduplicated file system within 50GB storage per host, while starting up within 2 -- 3 seconds on average.