Fast creation of short-living virtual machines using copy-on-write RAM-disks

Abstract

We propose a method to rapidly launch new virtual machines (VM), starting from a prepared copy-on-write (COW) snapshot image. W e use RAM-disks instead of stored ones and apply the COW technique on them, also. A VM can extend its RAM-disk on non-volatile storage area when it grows over an established threshold, just to avoid overloading the RAM. Our solution is appropriate in situations like testing environments with short-living VMs, where the VM persistence is not a requirement, b u t one just needs to start very fast new running VMs in a known safe state. W e implemented our solution in QEMU/KVM. The performance tests showed an improvement in the total VM's creation and running time of about 15% over the basic HDD-based method.