Changes

* '''Differencing''' - Differencing is a concept which involves a parent disk and a child disk. The parent disk contains a baseline hard disk image with the operating system and perhaps a range of applications and data installed. Once this baseline parent disk is configured, a differencing disk is assigned as a child. When the virtual machine to which the disk is assigned runs, any changes made the baseline parent image are actually stored on the child differencing disk, leaving the parent disk unaltered. Multiple child disks may be assigned to a parent disk allowing multiple virtual machines to share the same parent disk. The changes contained in a differencing disk may be merged into the parent disk. Alternatively, a new virtual hard disk may be created containing the merger of the parent disk and the child disk, thereby leaving the parent disk unaltered. When creating a differencing disk, the parent disk will need to be specified. The size of the differencing disk increases as space is required.Differencing disks may also be compacted to free up unused space (see the section below entitled Modifying Virtual Hard Disks). Once a disk type has been selected, click ''Next'' to specify a name and location for the virtual disk. Any location accessible to the host system may be used, or the default location used. Clicking ''Next'' proceeds to the ''Configure Disk'' screen shown below:  [[Image:hyper-v_configure_virtual_hard_disk.jpg|Configuring a Hyper-V Virtual Hard Disk]]  After selecting the initial size of the disk, the option is then provided to clone the image of a physical disk into the new virtual hard disk, allowing an existing operating system configuration to be duplicated on the virtual hard disk. A list of physical hard disk drives detected on the host system is provided for selection. After clicking ''Next'' the summary screen is displayed. Clicking ''Finish'' initiates the disk creation process. == Modifying Hyper-V Virtual Hard Disks ==