How to create a virtual hard disk on Windows 10

What Is Virtual Drive in Windows 10

In Windows 10, a Virtual Drive refers to a digital emulation of a physical disk drive. Unlike a physical hard drive that is tangible and occupies physical space, a virtual drive exists purely as a file on your system but behaves like a physical disk. This virtual disk can be a Virtual Hard Disk (VHD) or a Virtual Machine Disk (VMDK), among other formats, depending on the software used to create it.

A virtual drive allows you to mount disk images (such as ISO files), creating a "drive" that your system treats as if it were a real, physical disk. This feature is particularly useful for running different operating systems, testing software in isolated environments, backing up your system, or managing disk images without needing additional hardware.

Windows 10 includes built-in support for mounting, creating, and managing virtual drives through the Disk Management tool and PowerShell commands. For instance, you can mount an ISO file directly in File Explorer by double-clicking it, creating a virtual drive that allows you to access its contents as if you had inserted a physical disc into a disc drive. Similarly, you can use Disk Management or PowerShell to create and attach VHD files, which appear as new drive letters in File Explorer, enabling you to interact with them like any other disk drive.

This functionality enhances flexibility and convenience for users who need to access or test software, operating systems, and data stored in disk images without the need for additional physical drives, making it an invaluable tool for developers, IT professionals, and general users alike.

How does a virtual hard drive work?

A Virtual Hard Drive (VHD) operates by simulating the functionality of a physical hard disk drive within a computer system, but it does so entirely within software. Here's an overview of how VHDs work:

Creation and Storage

• File-Based Representation: A VHD is essentially a file or set of files that reside on a physical storage device, like an SSD or HDD. This file encapsulates the entire structure of a virtual disk, including the boot record, filesystem, files, and folders, mimicking the structure of a physical hard disk.
• Dynamic or Fixed Size: When creating a VHD, you can choose between a dynamically expanding disk, which grows as data is added, or a fixed-size disk, which allocates all the designated space immediately. This flexibility allows for efficient storage management based on the user's needs.

Integration with the Host System

• Mounting: The VHD file can be mounted by the operating system, making the virtual disk accessible as if it were a physical drive. Once mounted, it receives a drive letter, and users can interact with it—reading from and writing to it—using standard file operations.
• Isolation: Despite being accessible from the host system, the contents and operations within a VHD are isolated from the host's physical disks. This isolation ensures that actions within the VHD do not directly affect the host system's data or operation, making VHDs ideal for testing applications or running separate operating systems.

Operation

• File System Compatibility: Inside the VHD, a file system is maintained (such as NTFS for Windows), allowing software and operating systems within the VHD to operate as if they were on a physical disk. This includes executing programs, saving files, and performing disk operations.
• Snapshot and Backup: Some virtualization platforms offer the ability to take snapshots of VHDs, capturing the exact state of the virtual disk at a specific point in time. This is particularly useful for backup and recovery purposes, as well as for testing different configurations or software states.

Virtualization Platforms

• Hypervisors and Virtual Machines: VHDs are commonly used by virtualization software (like Microsoft Hyper-V, VMware, or VirtualBox) to create and run virtual machines (VMs). Each VM can use one or more VHDs as its storage, allowing for multiple, independent virtual systems to run on a single physical host.

Performance

• Dependent on Physical Storage: While a VHD is virtual, its performance is still dependent on the underlying physical storage device's capabilities. Operations within a VHD can be slower than those on a direct physical disk due to the additional layer of abstraction and file system overhead.

In essence, a VHD functions by creating a virtual abstraction layer over physical storage, offering flexibility, safety, and isolation for various computing needs without requiring additional physical hardware. This technology enables diverse applications, from software testing and development to data portability and disaster recovery strategies.

Create a virtual hard disk (VHD or VHDX file) in Hyper-V Manager

Creating a Virtual Hard Disk (VHD or VHDX) using Hyper-V Manager in Windows involves a series of steps that allow you to set up a new virtual disk for use with virtual machines. Here's how to do it:

Prerequisites

Ensure that Hyper-V is enabled on your Windows system. Hyper-V is available on Windows 10 Pro, Enterprise, and Education editions, as well as on Windows Server versions.

Step 1: Open Hyper-V Manager

• You can access Hyper-V Manager by typing "Hyper-V Manager" in the Start menu search bar and selecting it from the results.

Step 2: Access the Hyper-V Host

• In the Hyper-V Manager, in the left pane, select the Hyper-V host (your computer) to manage. If you haven’t added a server, you might need to connect to one by right-clicking on "Hyper-V Manager" in the left pane and selecting "Connect to Server".

Step 3: Open the New Virtual Hard Disk Wizard

• In the right pane, under the "Actions" section, click on "New" and then select "Hard Disk" to open the New Virtual Hard Disk Wizard.

Step 4: Choose the Disk Format

• Choose Disk Format: On the "Choose Disk Format" page, select either VHD for compatibility with older systems or VHDX for newer systems that support larger sizes and have improved performance and resilience features. Click "Next" to continue.

Step 5: Choose the Disk Type

• Select Disk Type: You have the option to create a dynamically expanding disk, a fixed size disk, or a differencing disk. A dynamically expanding disk starts small and grows as data is added (up to the maximum size you set), a fixed size disk allocates all the specified space immediately, and a differencing disk is a type of dynamically expanding disk that stores changes in relation to another disk. Choose the appropriate option and click "Next".

Step 6: Specify Name and Location

• Specify Name and Location: Enter a name for your VHD/VHDX file and choose a location to store it. It’s a good practice to store virtual disks in a location with ample space. Click "Next" to proceed.

Step 7: Configure Disk

• Specify the Disk Size: Enter the size for your new virtual hard disk. You can allocate the size in gigabytes (GB) or terabytes (TB), depending on your needs. For a dynamically expanding or differencing disk, this size is the maximum size the disk can grow to.
• For a Differencing Disk: If you chose to create a differencing disk, you would also need to specify the parent disk.

Step 8: Complete the Wizard

• Review your settings in the summary page, and if everything looks correct, click "Finish" to create the virtual hard disk.

Using the Virtual Hard Disk

After creating the VHD or VHDX file, you can attach it to a virtual machine by editing the VM's settings in Hyper-V Manager. Go to the "Settings" of the VM, add a hard drive under the SCSI Controller or IDE Controller, and then select the virtual hard disk you created.

This virtual hard disk can now be used by the virtual machine for storage, operating system installation, or other purposes, just like a physical hard disk.

Create a virtual hard disk (VHD or VHDX file) in Command Prompt

Creating a Virtual Hard Disk (VHD or VHDX) using the Command Prompt in Windows involves using the diskpart utility, a powerful command-line tool for managing disk partitions and volumes. Here's how you can create a new VHD or VHDX file using diskpart:

Step 1: Open Command Prompt as Administrator

• Right-click the Start button and select "Command Prompt (Admin)" or "Windows Terminal (Admin)" to run the Command Prompt with administrator privileges. If "Command Prompt" is not directly listed, you might need to select "Windows PowerShell (Admin)" or use the Windows Terminal and then switch to the Command Prompt profile.

Step 2: Start DiskPart

• At the Command Prompt, type diskpart and press Enter. This will start the diskpart utility.

Step 3: Create the VHD or VHDX

Within diskpart, you'll use the create vdisk command to create your virtual disk. Here are the commands step by step:

To Create a VHD:

• Replace "C:\path\to\your\newVHD.vhd" with the path and file name where you want to save the VHD.
• Change maximum=10000 to your desired size in megabytes. For example, 10000 for 10GB.
• Use type=fixed for a fixed disk or type=expandable for a dynamically expanding disk.

To Create a VHDX:

• The process is the same as for VHD, but ensure your file extension is .vhdx for the VHDX format, which supports larger disk sizes and is more resilient to power failure issues.

Step 4: Exit DiskPart

After creating your virtual disk, type exit to leave the diskpart utility.

Step 5: Attach the VHD/VHDX (Optional)

If you immediately need to use the newly created VHD or VHDX, you can attach it using diskpart by following these additional steps:

1. Start diskpart again.
2. Type select vdisk file="C:\path\to\your\newVHD.vhd" to select your VHD/VHDX file.
3. Type attach vdisk to attach the virtual disk to your system.

Notes

• The diskpart utility is very powerful and can make significant changes to your system's disks. Be cautious and ensure you're entering commands correctly.
• Creating a VHD/VHDX via Command Prompt provides a scriptable and automatable approach to managing virtual disks, suitable for integration into batch files or automated deployment scripts.

This method gives you a quick way to create a virtual disk directly from the Command Prompt, leveraging Windows' built-in disk management capabilities.