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Recover data from damaged or formatted VMFS disks or VMDK files
Last updated: Dec 02, 2024

How to Convert VHD to VMDK

When managing virtual environments, the need to convert disk formats often arises, especially when transitioning between different hypervisors. Virtual Hard Disk (VHD) is commonly used by Microsoft Hyper-V, while Virtual Machine Disk (VMDK) is the format preferred by VMware. Whether you’re migrating virtual machines or testing across multiple platforms, converting VHD to VMDK is essential to ensure compatibility and seamless operation. In this guide, we’ll walk you through the steps to convert VHD to VMDK, ensuring a smooth transition between virtual environments.

Understanding VHD and VMDK Formats

VHD and VMDK Files

Virtual Hard Disk (VHD) and Virtual Machine Disk (VMDK) are two key formats used to store the virtual hard drive data for virtual machines (VMs). A VHD file is the native disk format for Microsoft’s Hyper-V hypervisor, designed to emulate the functionality of a physical hard disk but within a virtual environment. VHDs store the operating system, applications, and data of a virtual machine, allowing it to function as if it were running on actual hardware. There are two primary types of VHDs: fixed-size and dynamically expanding. Fixed-size VHDs allocate all the storage space upfront, while dynamically expanding VHDs grow as data is written to them, offering more flexibility in managing storage.

VMDK files, on the other hand, are native to VMware products, including VMware Workstation, VMware Fusion, and VMware ESXi. Like VHDs, VMDKs serve as virtual containers for a virtual machine’s operating system, applications, and data. VMDKs can also be used in a variety of configurations, such as thin provisioning, where storage is allocated on demand, or thick provisioning, where full storage is reserved upfront. While VHDs and VMDKs serve the same purpose of encapsulating virtual machine data, they are not natively compatible with each other, requiring a conversion process when switching between hypervisors.

Use Cases for VHD to VMDK Conversion

The need to convert VHD files to VMDK often arises when users or organizations transition from a Microsoft Hyper-V environment to a VMware-based infrastructure. This may occur for a variety of reasons, such as the adoption of VMware’s more advanced virtualization management features, enhanced scalability, or more efficient resource management capabilities. Converting VHD to VMDK allows users to retain their existing virtual machines without the need to rebuild them from scratch when moving to VMware products.

One common use case for VHD to VMDK conversion is cloud migration. As organizations move their virtual machines between different cloud providers that utilize different virtualization platforms, conversion is necessary to ensure the VMs can continue to function seamlessly in their new environment. For example, a company may initially deploy a virtual machine on Microsoft’s Azure platform, which uses VHD, and later decide to migrate that machine to VMware’s vSphere environment running on AWS, which requires VMDK.

Another significant use case is cross-platform testing and development. Developers and system administrators may need to test software or configurations across multiple virtual platforms to ensure compatibility or to benchmark performance. In such cases, converting between VHD and VMDK enables virtual machines to run across different hypervisors without the need to duplicate setups, saving time and resources.

Additionally, disaster recovery scenarios often necessitate VHD to VMDK conversion. If an organization’s primary environment uses Hyper-V but its disaster recovery site relies on VMware, converting the VHD files to VMDK ensures that virtual machines can be quickly restored and brought online in the event of a failure. This flexibility allows businesses to design robust disaster recovery strategies that include diverse virtualization environments.

The Importance of Converting VHD to VMDK

Why Convert VHD to VMDK?

Converting VHD to VMDK is a critical task when transitioning virtual machines between different hypervisors. Each virtual disk format is tailored to a specific platform, with VHD primarily used by Microsoft Hyper-V and VMDK by VMware products. When businesses or individuals switch from one virtualization solution to another—whether due to preference, compatibility, or performance improvements—converting VHD to VMDK becomes essential. This conversion allows virtual machines to run seamlessly in their new environment without requiring extensive reconfiguration or data migration.

One of the main reasons to convert VHD to VMDK is to take advantage of VMware’s advanced features. VMware offers enhanced capabilities such as superior snapshot management, fault tolerance, and better support for large-scale enterprise environments. By converting to VMDK, users can tap into VMware’s robust ecosystem, including tools like vSphere, vCenter, and VMware Workstation, which are designed for optimizing virtual environments. Additionally, VMware’s VMDK format can handle larger virtual disks and is often more efficient in terms of resource allocation and management, making it the ideal choice for businesses with complex virtualization needs.

Furthermore, organizations often convert VHD to VMDK as part of a broader cloud migration or hybrid cloud strategy. In such cases, the goal is to ensure that virtual machines can operate across different cloud infrastructures, many of which support VMware. This interoperability allows businesses to maintain flexibility in their cloud deployments and to leverage the strengths of multiple platforms without locking themselves into a single vendor.

What Can You Do for the Safety of VHD and VMDK Files?

Ensuring the safety and integrity of your VHD and VMDK files during and after conversion is paramount. Data corruption or file loss can lead to downtime, disrupted services, and costly recovery efforts. Therefore, implementing a few best practices can help safeguard your virtual machine files throughout the conversion process.

Firstly, always create backups of your original VHD files before initiating the conversion to VMDK. Having a reliable backup ensures that, in case something goes wrong during the conversion, you can restore the original virtual machine without data loss. It’s advisable to store these backups in a separate location, whether on an external hard drive, a dedicated backup server, or in the cloud. This guarantees redundancy and protects your data from accidental deletion or hardware failures.

Secondly, verify the integrity of both your VHD and VMDK files before and after conversion. Use built-in tools like Microsoft Hyper-V’s Checkpoint feature for VHDs or VMware’s VMFS Health Check for VMDKs to ensure the files are not corrupted. Additionally, running a test deployment of the converted VMDK on a non-production environment is a smart approach to verify the conversion’s success without risking live operations.

Moreover, consider encryption and access control for both VHD and VMDK files, particularly if they contain sensitive or critical data. Virtual machines are prone to security risks like unauthorized access or tampering. Encrypting the virtual disks adds an extra layer of security, ensuring that even if files are accessed without permission, the data remains protected. Implementing proper access controls, including role-based permissions, ensures that only authorized personnel can modify or convert virtual disk files.

Lastly, regularly monitor and update the software used for managing and converting VHD and VMDK files. Whether using third-party conversion tools or native solutions provided by VMware and Microsoft, keeping the software up-to-date helps avoid vulnerabilities and ensures compatibility with the latest hypervisor versions. Regular updates also provide access to performance improvements, further safeguarding the reliability of your VHD and VMDK files during conversion.

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How to Convert VHD to VMDK

How to Open VHD and VMDK Files with DiskInternals

DiskInternals is a powerful tool that provides an easy way to open and manage virtual disk files like VHD and VMDK. This software is particularly useful for users who need to explore the contents of a virtual disk without loading the full virtual machine. To open a VHD or VMDK file using DiskInternals, follow these steps:

  1. 1. Download and install DiskInternals: First, ensure you have the latest version of DiskInternals available on your system. The software is compatible with both Windows and Linux platforms, making it versatile for different environments.
  2. 2. Open the software: Launch DiskInternals and navigate to the “Open” option in the menu. You will be prompted to select a disk image file.
  3. 3. Browse and select your VHD or VMDK file: Locate the file on your system and click "Open." DiskInternals will load the virtual disk and display its contents in a file explorer-like interface.
  4. 4. Explore and manage the contents: Once the file is open, you can browse through the folders and files stored within the virtual disk. DiskInternals allows you to extract data, recover deleted files, or even repair damaged files within the virtual disk.

Opening VHD or VMDK files using DiskInternals is especially useful if you need to verify the contents of the virtual disk before or after conversion. It provides a reliable way to ensure that no data is lost or corrupted during the process.

Qemu-img to Convert VHD to VMDK on Linux or Windows

Qemu-img is a powerful command-line tool used for converting and managing virtual disk images. It's widely used across both Linux and Windows platforms due to its flexibility and support for various disk formats, including VHD and VMDK. To convert a VHD to VMDK using Qemu-img, follow the steps below:

  1. 1. Install Qemu-img: If you don’t already have Qemu-img installed, you’ll need to download it. On Linux, you can install it by running:

sudo apt-get install qemu-utils

For Windows, you can download the precompiled Qemu-img binary from the Qemu website.

  1. 2. Locate your VHD file: Ensure that the VHD file you want to convert is stored on your system and accessible. Also, decide on the destination path where the converted VMDK file will be saved.
  2. 3. Run the conversion command: Open a terminal (or command prompt on Windows) and use the following syntax to convert your VHD to VMDK:

qemu-img convert -f vpc -O vmdk source.vhd destination.vmdk

Here, -f vpc specifies that the source format is VHD (VPC), and -O vmdk tells the tool to output in the VMDK format. Replace source.vhd with the path to your VHD file, and destination.vmdk with the path where you want to save the converted VMDK.

  1. 4. Verify the conversion: Once the conversion process completes, you can verify the integrity of the newly created VMDK file by loading it into a VMware product, such as VMware Workstation or vSphere. This ensures that the virtual machine can boot and operate normally using the VMDK format.

Best Practices for VHD to VMDK Conversion

Ensuring Data Integrity Post-Conversion

When converting a VHD file to VMDK, ensuring data integrity is crucial to avoid file corruption, data loss, or malfunctioning virtual machines. To safeguard your data during the conversion, always start by creating a backup of the original VHD file. This backup serves as a safety net, allowing you to revert to the original disk image in case of any errors during the conversion process.

It’s also important to choose a reliable and tested conversion tool. Tools like Qemu-img or third-party software such as DiskInternals provide proven functionality and minimize the risk of data corruption. Running a checksum comparison before and after conversion can also help verify that the data has not been altered. In addition, ensure your storage medium is stable, with enough space available to accommodate both the original VHD file and the newly converted VMDK file. Low disk space or faulty hardware can increase the risk of corruption.

Finally, avoid making any changes to the virtual machine or disk contents during the conversion process. It’s best to power off the virtual machine, ensuring no active operations or I/O processes are ongoing, as these can interfere with the integrity of the disk image.

Verifying VMDK File Integrity

After converting a VHD to VMDK, verifying the integrity of the VMDK file is essential before deploying it in production or mission-critical environments. Start by loading the VMDK into VMware Workstation, VMware ESXi, or another compatible platform. Once the VMDK is mounted, boot the virtual machine and check for any errors during startup. A properly converted file should allow the VM to boot normally, with all the expected data and configurations intact.

You can also run disk checking utilities on the virtual machine to ensure that the virtual hard drive has no errors. VMware’s built-in tools, such as vmkfstools or esxcli, can be used to check the file structure and overall health of the VMDK file. For example, you can use the vmkfstools -x check command to check and repair errors on a VMDK disk.

If the virtual machine does not boot or encounters errors, it’s a sign that the conversion may have failed, or the VMDK file may have become corrupted. In this case, reverting to the original VHD file and attempting the conversion again may be necessary. Always ensure that you are using the latest version of the conversion tool to avoid software-related issues.

Optimizing VMware Settings After Conversion

Once the VHD to VMDK conversion is complete and the virtual machine is running smoothly, optimizing VMware settings can improve performance and stability. One of the first optimizations is adjusting the disk type to match your use case. For instance, after the conversion, you can switch the virtual disk from a thick provisioned VMDK (default) to a thin provisioned one to save storage space. Thin provisioning allows the disk to dynamically grow based on the actual data stored, reducing the initial disk footprint.

Additionally, fine-tuning the VM’s CPU, memory, and resource allocation settings is key to optimizing performance, especially if the virtual machine was originally configured for Hyper-V and now runs in VMware. VMware’s resource management features, such as Distributed Resource Scheduler (DRS) and memory ballooning, can help balance resource distribution across virtual machines, especially in larger environments.

Furthermore, VMware tools should be installed or updated within the virtual machine to ensure better integration with VMware’s features. These tools provide drivers and utilities that enhance performance, such as better network handling and disk performance optimization. Lastly, enabling advanced features like snapshots and fault tolerance can improve your VM's data protection and recovery capabilities in VMware.

Top 3 Free Tools for Converting Between VHD and VMDK Formats

  • StarWind V2V Converter: This tool is specifically designed to convert virtual disk images between various formats, including VHD and VMDK. It is lightweight, easy to use, and does not require installation, making it a convenient choice for quick conversions.
  • VMware Converter Standalone: While primarily geared towards converting physical machines to virtual machines, this tool also supports converting existing virtual machines between different platforms. It can handle VHD to VMDK conversions and vice versa, particularly useful for users migrating to or from VMware.
  • WinImage: Although more commonly known as a disk imaging software, WinImage supports converting between VHD and VMDK formats. It provides additional features like editing, creating, and extracting disk images, which can be beneficial if you need more than just format conversion.

VMFS Recovery for VMDK Files Recovery

VMFS recovery tools, such as DiskInternals VMFS Recovery, are designed to specifically target and restore data from damaged VMFS volumes. These tools scan the entire VMFS structure for lost or corrupted VMDK files and offer a step-by-step recovery process. DiskInternals VMFS Recovery, for example, uses advanced algorithms to rebuild VMDK files, even if the VMFS partition itself is damaged or unreadable. It also supports RAID arrays, which are commonly used in virtual environments, making it a comprehensive solution for VMFS recovery.

Using a tool like DiskInternals VMFS Recovery, you can recover VMDK files from formatted, corrupted, or inaccessible VMFS volumes without the need to take your entire VMware infrastructure offline. This ensures minimal disruption to your operations and a higher chance of successfully retrieving vital data. The software also provides a preview feature that allows users to check the integrity of the recovered files before proceeding with full recovery.

Conclusion

Converting VHD to VMDK is a critical task for users who want to transition between Microsoft Hyper-V and VMware environments, whether for cloud migration, testing, or disaster recovery. Ensuring data integrity during and after conversion is paramount, and using trusted tools such as Qemu-img or DiskInternals can greatly simplify the process. Post-conversion, verifying and optimizing the VMDK file within VMware ensures a smooth and efficient transition. Additionally, when VMDK files stored on VMFS volumes become corrupted, tools like DiskInternals VMFS Recovery provide reliable solutions to recover and restore lost data, ensuring business continuity and minimizing downtime. With the right tools and best practices, VHD to VMDK conversion can be a seamless and secure process that opens the door to enhanced virtualization flexibility.

FAQ

  • What is the difference between VHD and VMDK?

    VHD (Virtual Hard Disk) is the native disk format used by Microsoft Hyper-V, while VMDK (Virtual Machine Disk) is the format used by VMware products like VMware Workstation and VMware ESXi. Both formats serve as virtual containers for operating systems, applications, and data within virtual machines, but they are not interchangeable between Hyper-V and VMware environments without conversion.

  • Why would I need to convert VHD to VMDK?

    You would need to convert a VHD to VMDK when migrating a virtual machine from a Microsoft Hyper-V environment to a VMware environment. This conversion ensures that the virtual machine can operate correctly on VMware’s virtualization platform without needing to be rebuilt from scratch.

  • What tools can I use to convert VHD to VMDK?

    You can use several tools to convert VHD to VMDK, including Qemu-img, a command-line utility available for Linux and Windows. Third-party tools like DiskInternals can also help with conversions, providing a more user-friendly interface. These tools ensure compatibility between different hypervisors by converting disk formats.

  • How can I ensure the safety of my data during the conversion?

    Before converting a VHD to VMDK, it’s essential to create a backup of the original VHD file to prevent data loss. Additionally, using reliable conversion tools like Qemu-img or DiskInternals, and verifying the file integrity post-conversion, can help ensure that your data remains intact.

  • How can I verify the integrity of my VMDK file after conversion?

    After conversion, load the VMDK file into a VMware product like VMware Workstation or vSphere to ensure the virtual machine boots properly. You can also use built-in tools like vmkfstools to check and repair any errors in the VMDK file. Running a test environment with the converted virtual machine helps ensure everything is functioning as expected.

  • What should I do if my VMDK file becomes corrupted?

    If your VMDK file becomes corrupted, tools like DiskInternals VMFS Recovery can help recover data from damaged or inaccessible VMFS volumes. These tools can scan and restore lost or corrupted VMDK files, even if the VMFS partition itself is damaged.

  • Can I convert VHD to VMDK on both Linux and Windows?

    Yes, Qemu-img is a versatile command-line tool that works on both Linux and Windows platforms. It allows you to convert VHD to VMDK and other formats with a simple set of commands, making it a popular choice for system administrators and developers.

  • What VMware settings should I optimize after conversion?

    After converting to VMDK, consider optimizing settings such as disk provisioning (e.g., switching from thick to thin provisioning) and adjusting CPU, memory, and resource allocation to match the VMware environment. Installing VMware Tools on the virtual machine can also improve performance and enhance the integration with VMware’s features.

  • Can I recover VMDK files from a damaged VMFS volume?

    Yes, specialized tools like DiskInternals VMFS Recovery are designed to recover VMDK files from damaged or corrupted VMFS volumes. These tools scan the VMFS structure and attempt to rebuild the VMDK files, ensuring you can restore your virtual machines even if the VMFS volume is unreadable.

  • Is there any risk in converting virtual disk formats?

    While converting virtual disk formats is generally safe when done correctly, there is always a small risk of data corruption or loss. To mitigate this risk, always back up your data, use reliable tools for conversion, and verify the integrity of the converted file before deploying it in a production environment.

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