Optimizing Total Migration Time in Virtual Machine Live Migration

The ability to migrate a virtual machine (VM) from one physical host to another is important in a number of cases such as power management, on-line maintenance, and load-balancing. The amount of memory used in VMs have been steadily increasing up to several gigabytes. Consequently, the time to migrate machines, the total migration time, has been increasing. The aim of this thesis is to reduce the total migration time. Previous work aimed at reducing the amount of time and disk space required for saving checkpoint images of virtual machines by excluding data from the memory that is duplicated on the disk of the VM. Other work aimed at reducing the time to restore a VM from a checkpoint by only loading a subset of data before resuming the VM and marking the other memory as invalid. These techniques have been adapted and applied to virtual machine live migration to reduce the total migration time. The implemented technique excludes sending duplicate data that exists on disk and resumes the VM before all memory has been loaded. The proposed technique has been implemented for fully virtualized guests in Xen 4.1. The results of research conducted with a number of benchmarks demonstrate that there is an average 44% reduction of the total migration time