Explain the VHD files under win7 system and their different types.

What are VHD files, what is the role of VHD, how to use VHD files, and how many types of VHD files? Many users who use virtual machines sometimes have a little knowledge, not to mention those who have not touched the virtual machine. It is not known, so let's take a look at the VHD files and their various types under Windows 7 system.

First, what is a VHD file?

First of all, Microsoft's VHD file format is a virtual machine hard disk, and can be compressed into a single file to be stored in the host machine's file. On the system, it mainly includes the system files required for the virtual machine to start.

About VHD application: Virtual PC is a kind of windows virtual machine, it can virtualize various versions of windows, one windows should be installed on a hard disk partition, and it is virtual windows, it is impossible to draw separately Out a hard disk partition to install it, so it starts the required system files are compressed into a VHD format file placed on the hard disk.

The VHD format will also be used for Microsoft Windows Server 2008 R2 and Microsoft Windows 7, including hypervisor-based virtualization technology - Hyper-V. Hyper-V can operate VHD &mdash offline; allowing administrators to securely access the system through a VHD file, and administrators can access and perform some offline management tasks on virtual files (VHDs).

The VHD format is also available in the Business, Enterprise and Ultimate editions of Windows Vista for full system backup.

Second, multiple types of VHD files

1. Fixed VHD

The fixed virtual disk size of the fixed VHD file is the virtual disk size specified when the VHD was created. For example, if you create a virtual hard disk that is 2 GB in size, the system creates a file that is approximately 2 GB in size, some of which is used for the internal VHD structure. The size of a fixed VHD does not change as data is written to the virtual hard disk.

2, Scalable or Dynamic VHD

At any given time, the size of an expandable or dynamic VHD file is the same as the actual data size written to the file. As more data is written, the file is dynamically increased. For example, a file that supports a 2 GB virtual hard disk is initially about 2 MB in the host file system. As data is continuously written to this virtual hard disk, the file grows until it reaches the 2 GB capacity limit.

3, Difference VHD

Difference VHD is similar to a dynamic VHD, but only contains modified virtual disk blocks of the associated parent virtual disk. The differential VHD is linked to a specific parent VHD, called a child VHD. The parent VHD file is read-only; all modifications are made to the child VHD. The VHD file type of the parent VHD can be any of these three VHD types, including another differential VHD. Multiple sub-VHD files can form a differential chain.

After the above detailed introduction, we can understand that the VHD file is the virtual machine hard disk on the system, mainly including the files required for the virtual machine to start, and has different uses for different types of VHD files. Users can learn more and believe that it is helpful to use virtual opportunities.