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VHDX is the Virtual Hard Drive file name used in the 2012 version. &nbsp;The AVHDX filename is actually the &quot;delta&quot; (difference) file that is created when you make snapshots. Since you say you didn't create any it's strange ... Can you check if you can delete the snapshot (if there is any)? If you delete the snapshot and then power down the VM the files should &quot;dissapear&quot;, it can take a moment, since they need to merge...
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VHDX is the Virtual Hard Drive file name used in the 2012 version.  The AVHDX filename is actually the "delta" (difference) file that is created when you make snapshots. Since you say you didn't create any it's strange ... Can you check if you can delete the snapshot (if there is any)? If you delete the snapshot and then power down the VM the files should "dissapear", it can take a moment, since they need to merge...

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how do I find these snapshots? :-)
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You might find some useful info <a href="https://gilgrossblog.wordpress.com/2014/05/02/cant-remove-hyper-v-backup-checkpointsnapshot-from-vm/" rel="ugc">here</a>
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You might find some useful info here [https://gilgrossblog.wordpress.com/2014/05/02/cant-remove-hyper-v-backup-checkpointsnapshot-from-vm/]

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You don't need to find them, do not delete them from the file system.<br />
<br />
remove them through the menu.<br />
<br />
<a href="http://social.technet.microsoft.com/wiki/contents/articles/211.hyper-v-virtual-machine-snapshots-faq.aspx" rel="ugc nofollow"><b>Hyper-V Snapshots FAQ</b></a>
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You don't need to find them, do not delete them from the file system.

remove them through the menu.

Hyper-V Snapshots FAQ [http://social.technet.microsoft.com/wiki/contents/articles/211.hyper-v-virtual-machine-snapshots-faq.aspx]

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Hi Andrew - thnx for your input but your link does not work
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Hi Andrew - thnx for your input but your link does not work

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It works for me....<br />
<br />
<a href="http://social.technet.microsoft.com/wiki/contents/articles/211.hyper-v-virtual-machine-snapshots-faq.aspx" rel="ugc nofollow">http://social.technet.microsoft.com/wiki/contents/articles/211.hyper-v-virtual-machine-snapshots-faq.aspx</a>
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It works for me....

http://social.technet.microsoft.com/wiki/contents/articles/211.hyper-v-virtual-machine-snapshots-faq.aspx [http://social.technet.microsoft.com/wiki/contents/articles/211.hyper-v-virtual-machine-snapshots-faq.aspx]

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Someone took a snapshot/checkpoint as mentioned.<br />
<br />
When this happens a differencing disk is created for any changes post snapshot/checkpoint. That is the AVHDX file.<br />
<br />
For obvious reasons if storage is already thinly provisioned or fully provisioned with fixed VHDX files having a growing differencing disk or disks is perilous to the entire setup. As soon as that storage runs out all VMs with VHDX files on that storage go into a Paused - Critical state.
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Someone took a snapshot/checkpoint as mentioned.

When this happens a differencing disk is created for any changes post snapshot/checkpoint. That is the AVHDX file.

For obvious reasons if storage is already thinly provisioned or fully provisioned with fixed VHDX files having a growing differencing disk or disks is perilous to the entire setup. As soon as that storage runs out all VMs with VHDX files on that storage go into a Paused - Critical state.

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Ok I appreciate the information but how do I change this?
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Ok I appreciate the information but how do I change this?

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I have a pc running Windows 8.1.<br />
My plan was to use Hyper-V for some virtual Windows 7 machines.<br />
For some strange reason the virtual hard drives has changed to AVHDX format.<br />
I know that this has something to do with snap shots / recovery points but I don't recall making these.<br />
How do I convert back to VHDX?<br />
<br />
Looking forward to your inputs :-)
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I have a pc running Windows 8.1.
My plan was to use Hyper-V for some virtual Windows 7 machines.
For some strange reason the virtual hard drives has changed to AVHDX format.
I know that this has something to do with snap shots / recovery points but I don't recall making these.
How do I convert back to VHDX?

Looking forward to your inputs :-)

Why does my virtual machines convert to AVHDX files?

Hyper-V is a native hypervisor; it can create virtual machines on x86-64 systems and supersedes Windows Virtual PC as the hardware virtualization component of the client editions of Windows NT. A server computer running Hyper-V can be configured to expose individual virtual machines to one or more networks. Hyper-V Server supports remote access via Remote Desktop Connection. Administration and configuration of the host OS and the guest virtual machines is generally done over the network.

Hyper-V

Virtualization is the act of creating a virtual (rather than actual) version of something, including (but not limited to) a virtual computer hardware platform, operating system (OS), storage device, or computer network resources. Virtualization is usually the creation of a system that executes separate from the underlying hardware resources, or the creation of an entire desktop for systems located elsewhere, similar to thin clients.

Virtualization

Windows 8 is a personal computer operating system developed by Microsoft as part of the Windows NT family of operating systems, with an emphasis on improving its user experience on tablets. In particular, these changes included a touch-optimized Windows shell based on Microsoft's "Metro" design language, the Start screen, a new platform for developing apps with an emphasis on touchscreen input, integration with online services, support for USB 3.0, Advanced Format hard drives, near field communications, and cloud computing. Additional security features were introduced, such as built-in antivirus software, integration with Microsoft SmartScreen phishing filtering service and support for UEFI Secure Boot on supported devices with UEFI firmware.