One of the most important feature of Hyper-V, present in Windows Server 2012, is the Replica. This feature allows to create a copy of VM from host to another faster and easier. Over the classic Disaster Recovery scenario, Replica can be used to migrate your VMs to a new infrastructure or to different domain.
But what happen if the old server is based on Windows Server 2008 R2? How we can move our VMs from Hyper-V 2008 R2 to new host based on Hyper-V 2012 R2? If we don't want pay, we can use the classic procedure export/import, but this operation may require few minutes for each VM, depends by the speed of disks where the data are exported.
The second way is use Veeam Backup & Replication, the software that allows you to create a Replica Job of VMs also if the OS versions are different between source and destination.