What is the difference between VHD and VHDX? When should they be used?

Used primarily with Microsoft's Hyper-V virtualization platform, these two disk image formats may sound similar but there are some key differences you should keep in mind before booting up your virtual machine.

What is VHD?

First of all, let's start with the VHD format.

VHD stands for Virtual Hard Drive and is a type of file format used to represent virtual hard drives. Basically, it is a disk image file format that includes the entire contents of a virtualized hard drive. VHD files are mainly used in virtualization environments, where they simulate the functionality of physical hard drives in virtual machines. VHD files can store operating systems, applications and data, making them an integral part of virtualization technology, and these virtual machines use and recognize these files as real hard drives. fact - you can mount them, unmount them and store other files on them.

It's a format first created by a company called Connectix in 2003, which has made the file specifications available for use by third parties since 2005. This format is primarily used by Microsoft for Virtual PC and later on its Hyper-V virtualization platform. , but it is also used by third-party virtualization programs such as Virtualbox and VMware.

What is VHDX?

On the other hand, VHDX is basically just a newer version of VHD. Microsoft decided to release a successor version of VHD to be able to overcome some of the shortcomings and remaining problems of VHD as well as make it more flexible in use. Microsoft currently uses VHDX files for Hyper-V, but unlike VHD, VHDX is not widely supported by third-party virtualization software. At the time of writing, Virtualbox and VMware instruct users to convert VHDX files to VHD if they want to use them on their virtual machines.

VHDX was first deployed in 2012 with the launch of Windows 8 and Windows Server 2012, and has since become the go-to format for all of Microsoft's virtualization work.

How are VHD and VHDX different?

There are some differences between VHD and VHDX. The most immediately noticeable thing is the maximum drive size. While VHD allows drives up to 2TB, VHDX raises the bar up to 64TB. While you won't need that much space unless you're a business user, this can be useful if you want more than 2TB in your virtual machine.

There are also some other differences. VHDX files support larger block sizes and better performance, especially with modern hardware and applications with advanced storage features. VHDX files also have better resilience, including features like protection against data corruption during power outages and a "logging" mechanism to track changes before they are committed to the file.

Since this is an enhanced version of VHD, VHDX really has no disadvantages. However, one downside to mention is that you can only really use VHDX files on Hyper-V, as most third-party virtualization software does not yet support them.

VHD vs VHDX: Which is better?

If you plan to use Hyper-V, VHDX is a no-brainer. This is the newer, most flexible, secure, and feature-rich format. But the fact that it's mostly incompatible with third-party virtualization software means you're limited to just Hyper-V with that format.

On the other hand, VHD is an older format. However, this is also widely documented and is used by essentially all virtualization software out there, so if you have a VHD file, you can use it on any virtual machine. any existing.

The main difference between VHD and VHDX comes down to what you value most: Use newer specifications or keep your files to specifications that can be used in third-party software. The decision is really up to you. It should also be mentioned that in addition to VHD and VHDX, there are other formats, including VMware's VMDK files and VirtualBox's VDI files.