Changes

* '''Dynamically Expanding''' - Dynamically expanding virtual hard disks start small and then automatically expand to provide more capacity on an as needed basis up to a maximum size specified at creation time. Note that the dynamic feature only applies to expansion. In other words, the virtual hard disk will not automatically decrease in size when data is removed. Dynamic expanding virtual hard disks may, however, be ''compacted'' to free up unused space.

* '''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. Differencing disks may also be chained together. 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 Existing Hyper-V Virtual Hard Disks).