Q. Is there an easy way to convert a physical disk or system to a Virtual Hard Disk (VHD)?

A. It's possible to convert a physical disk, including a system disk, into a VHD using many physical to virtual (P2V) convertor tools, such as System Center Virtual Machine Manager (SCVMM). These tools typically use a volume shadow copy to capture the disk content and then migrate the content into a VHD. They then create a virtual machine on a hypervisor host matching the hardware of the original physical box. Alternatively, P2V systems can have custom boot environments (often based on Windows PE) that capture the disk contents from outside of the OS. These systems typically require substantial infrastructure but have a lot of functionality.

You might want to simply convert a disk (even a system disk) to a VHD—doing so could be useful for P2V scenarios. Or you might want to take a physical disk and make it a VHD so you can use the features in Windows 7 and Windows Server 2008 R2 that let you boot from VHDs. Sysinternals offers a free tool called Disk2vhd to do this.

Once executed, the tool shows all volumes on your system. It lets you select which drives should be captured to a VHD and to where they should be captured. Once you've selected the volumes, click Create and the tool creates a differential snapshot. (You can see it with the "vssadmin list shadows" command). The data is then copied from the snapshot into a VHD, and then the snapshot is deleted. All of this is done with no down time.

It's important to note that the VHDs created by disk2vhd are fully bootable, unlike the VHDs created by Windows Backup. You can use disk2vhd to capture the system disk then take that VHD, copy it to a virtual server like Hyper-V, and use it as the boot volume.

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