Trying out the new features with Windows 2012 R2. One of the interesting features is the Live Export. In the previous versions of HyperV, its mandatory to keep the VM down while performing an export.
With Windows 2012 R2, that restriction is lifted out.
The idea which is getting used here is similar of a snapshot. While we take a snapshot, a differencing disk is created from that point which will have the updates. This disk will have the extension .avhdx (Advanced Virtual Hard Disk). In case of a restore, This ahvdx is discarded and the parent disk will be used. At the time of deleting a snapshot, the avhdx will get merged to vhdx.
In Windows 2012 R2, While we perform a live export – a snapshot is happening in the background which creates a avhdx file. All the updates will be happening to this differencing disk till the export gets completed. Once the export is completed, this avhdx will get merged to the parent disk.
Lets see how it works.
I am going to export a VM named VM1.
Please refer to the disk configuration of VM1. Now the VHDX configured is VM1.VHDX.
Triggering a live export from Powershell. Please note – We need to open the powershell on elevated mode.
While the export is in progress, Lets go back to the disk configuration and see the current disk.
Lets wait for the export process to complete. The progress will be visible on the HyperV Manager.
And once the export is done, We will see that merging in progress. At this stage, the avhdx disk which got created is getting mreged back to the parent vhdx – in this example, vm1.vhdx.
For any questions/suggestions, Feel free to drop as a comment.