What is a virtual hard disk?
A virtual hard disk (VHD or VHDX) is a file that behaves like a physical hard disk drive but does not contain any actual disk hardware. VHD files are used by virtualization platforms like Hyper-V and VMware to create virtual machines.
A VHD file contains a virtual hard disk partition where the operating system, applications, and data for a virtual machine are stored. When you create a new virtual machine, you must specify a VHD file for the VM’s hard disk. This VHD file serves as the container for the virtual disk space that is seen by the guest operating system inside the VM.
Some key characteristics of virtual hard disks:
- VHD files are stored as single files on a physical disk or network share.
- Common VHD file formats include VHD (Virtual Hard Disk), VHDX (Virtual Hard Disk Extended), and VMDK (Virtual Machine Disk).
- VHD files describe a virtual hard disk partition, including space for storing a file system, applications, and data.
- The guest OS inside a VM sees the VHD file as if it were a real physical disk drive.
- VHD files can be dynamically expanding or fixed size.
- A single VM can have multiple VHDs attached to expand disk space.
In summary, a virtual hard disk file allows you to create a virtualized hard drive for virtual machines. The VHD format provides portability and flexibility for managing virtual disk storage.
Why would you want to delete a virtual hard disk?
There are a few common scenarios where you may need or want to delete a virtual hard disk file:
- Remove unused or unneeded VMs – If you delete a virtual machine, you likely want to delete the associated VHD file as well to free up space. There is no reason to keep orphaned VHDs after the VM is gone.
- Replace with a new VHD – You might want to migrate a VM to a new VHD file to increase disk space, improve performance, or update the disk format.
- Temporary VMs – If you create short-lived VMs for testing purposes, you’ll want to remove the VHDs after.
- Rebuild a VM – If a VM is corrupted or needs to be rebuilt from scratch, deleting the VHD allows you to start fresh with a new virtual disk.
- Free up storage space – Deleting unneeded VHDs can help recover used storage capacity on physical disks.
- Consolidate VMs – You may want to copy VMs to a new location and delete the old VHD files.
- Wrong sized VHD – If you create a dynamically expanding VHD that grows too large, you may want to delete it and create a new fixed-size VHD.
In most cases, if you no longer need a VHD file, it’s best practice to delete it to save space and avoid cluttering up your virtual disk storage.
How do I delete a virtual hard disk file?
The process for deleting a virtual hard disk file depends on a few factors:
- Your virtualization platform – VMware, Hyper-V, VirtualBox, etc.
- Where the VHD file is stored – a local disk, external storage, or network share.
- Whether the VHD is attached to an existing VM or not.
Here are general guidelines for deleting VHDs on common virtualization platforms:
Hyper-V
To delete a VHD or VHDX file in Hyper-V:
- Open Hyper-V Manager.
- Locate the VHD file under the Virtual Hard Disks folder or subsystem.
- Right-click the VHD and select Delete.
- Confirm the file deletion.
If the VHD is attached to a VM, you must first detach it from the virtual machine configuration. Shut down the VM, edit settings, remove the virtual hard disk attachment, then confirm deletion.
VMware vSphere
To delete a VMDK virtual disk in vSphere:
- In vSphere Web Client, right-click on the VM and select Edit Settings.
- Under Virtual Hardware, select Hard disk and highlight the VMDK to remove.
- Click the Remove icon.
- In disk management, right-click on the detached VMDK and select Delete from Disk.
Again, make sure the VMDK is detached from any active VM before deletion.
VirtualBox
For VirtualBox VDI files:
- Open the Virtual Media Manager.
- Locate the VDI file you want to delete.
- Right click on the VDI and select Remove.
- Confirm deletion in the popup dialog.
As with other platforms, a VDI must be detached from a VM configuration before it can be deleted.
Other Platforms and Locations
The general process is similar across platforms – find the VHD file, right-click and delete, making sure it’s detached from any VM first.
If the VHD is on external or networked storage, you may need to go through the storage platform (vSAN, SMB share, etc.) to delete the file rather than the virtualization manager.
Some hosts may also support deleting VHDs from command line using utilities like rm or del, if preferred.
Can I recover a deleted VHD file?
If you accidentally delete a virtual hard disk file, recovery may be possible in some cases:
- If the VHD was on a local NTFS or ReFS formatted drive, recovery software can potentially restore the deleted file.
- If the VHD was on a SAN or NAS, check if the storage system has snapshots or backups you can use to retrieve the file.
- For VHDs on a Hyper-V failover cluster, there may be a saved replica you can recover from another node.
- Some backup applications like Veeam can restore deleted VHDs if they were previously backed up.
However, once a VHD file is manually deleted, full recovery becomes less likely over time as previously used disk space gets overwritten with new data. So the sooner you attempt recovery, the better.
If no backups or file recovery options are available, the VHD and its VM data are likely gone for good once deleted. This is why it’s critical to maintain backups of important VMs and VHDs before deletion.
Best practices when deleting virtual hard disks
Follow these best practices when deleting VHDs:
- Detach the VHD – Make absolutely sure the VHD is detached or disconnected from any virtual machine before deletion. Deleting an attached disk can corrupt the VM.
- Back up first – If the VHD contains important data, create backups before deleting. Backup key VMs on a regular basis.
- Confirm deletion – Double check you are deleting the correct VHD file before confirming file removal.
- Search for orphaned files – Periodically look for any orphaned VHDs no longer attached to VMs and delete them.
- Manage VHD lifecycles – Have a policy to archive or delete old VHDs from inactive VMs.
Following these tips will help avoid accidental data loss when removing virtual hard disks. Be thoughtful in your deletion process.
FAQs
Is deleting a VHD file the same as formatting a disk?
No, deleting a VHD is not the same as formatting a physical disk. When you format a disk, it simply clears the file system and marks all space as available for new data. The disk partition itself remains intact.
Deleting a VHD file removes the entire virtual disk partition. The file is discarded, so all data and structures on that virtual disk are lost. Deleting a VHD is more akin to physically destroying a real hard disk.
Can I destroy or shred VHD data?
Not directly on the VHD format itself. Because VHD files are just single files on the host filesystem, you can delete them but not selectively wipe or overwrite data inside the VHD.
However, some storage systems like SANs may provide a disk scrubbing or destruction feature that can wipe VHD data before deletion. Otherwise, you need to rely on traditional file deletion being sufficient.
Is it better to have fixed or dynamic VHDs?
Fixed VHDs allocate all disk space upfront when created. Dynamic VHDs start small but can grow as needed.
Fixed VHDs are preferred if you know the full size needed and want to avoid fragmentation issues. Dynamic VHDs allow more flexibility to add disk space later.
Consider your storage capacity, VM workloads and ability to estimate disk requirements when deciding between fixed or dynamic VHDs.
Can I mount a deleted VHD file if recovered?
Possibly, if you can fully recover the deleted VHD file and it has no corruption. Detach any existing mount points first.
Then, attempt to attach the recovered VHD to a VM as a new disk. If it mounts successfully, the file system and data may be accessible to recover files.
Is it better to delete VHDs using PowerShell/CLI instead of Hyper-V Manager?
PowerShell or CLI deletion offers some advantages:
- Automate deletion of multiple VHDs with scripts vs. manual work.
- Avoid accidentally selecting the wrong file in a GUI.
- Add logging or confirmation prompts before deletion.
- Integrate deletion into other provisioning or maintenance workflows.
So for admins who are comfortable with CLI/PowerShell, scripting deletions can be quicker and less error-prone. But the Hyper-V Manager GUI also works fine for one-off deletions.
Conclusion
Deleting unused virtual hard disks helps recover storage capacity and cleans up disk clutter after VMs are no longer needed. Always exercise caution when deleting VHDs – confirmdetachment, back up data, and be sure to select the correct file to prevent accidental data loss. Follow virtualization best practices for VHD lifecycle management to maximize your utilization of these critical files.