A friend of my was running his Hyper-V 2012R2 environment with differencing disks. Not so good for performance, so he asked if he could migrate them to normal disks.
Luckily I had played a bit with differencing disks in my lab environment to see how it works. So I could use this lab to test the migration path.
This is the parent disk which I used for all lab machines.
As you can see, the LB-DC01 is using this disk as it’s parent disk.
The LB-DC01 has a checkpoint. All checkpoints needs to be removed first.
When the checkpoint had been removed, its merged into it’s original disk. Notice the increased disk size.
Just to be sure, I export the machine to a save place as a backup.
When the export operation has finished, it created a complete copy of the vm, including a copy of the parent disk.
Now it’s time to merge the disk. At this point the vm needs to be turned off. Edit the disk and select the Merge option.
In the Configure Disk window, select To a new virtual hard disk and choose the appropriate hard disk type.
After the operations has finished, the new disk has been created.
The last step is to configure the vm and point the hard drive to the newly created vhdx file.
After starting the vm, everything works fine!