Hyper-V has always provided the ability to backup all your virtual machines from the host operating system. In order to provide a consistent backup of the virtual machine – Hyper-V has traditionally employed two approaches:
- If the guest operating system has the Hyper-V backup integration service installed and running: use VSS (for Windows) or file system freeze (for Linux) to create a data consistent backup of the running virtual machine.
- If the guest operating system does not have the Hyper-V backup integration service installed or running: put the virtual machine into a saved state, and perform a backup of the saved virtual machine.
This second approach has always been problematic – as it takes a running virtual machine offline for the backup process. The good news is that this second approach has been drastically improved in Windows Server 2012 R2. Now, rather putting the virtual machine into a saved state – we take a checkpoint of the virtual machine. This checkpoint is backed up, and deleted after the operation is complete.
The net result of this is that no matter what the guest operating system, and no matter what the state of the integration services inside the guest operating system, Hyper-V will never interrupt a running virtual machine as part of backing it up (anymore).