Hyper-V AVHDX is huge.  Disk is full.  Only one checkpoint.

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Apologies for the newbie question.  Hyper-V (Windows Server 2016).  AVHDX file is huge (600+GB).  The D: drive where vhx and avhdx files are stored is full.  Cannot extend D: volume because it is grayed out.  Have tried shrinking C: drive, can't.  

Can I COMPACT the AVHDX file?  Or should I MERGE it?  Or DELETE it?  Will attach a picture of the snapshot screen.
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Philip ElderTechnical Architect - HA/Compute/Storage

The catch with all checkpoints/snapshots is the need to create a new parent once those changes are merged back in. :(

You're stuck with manually merging things via this article.

Or, if you have a backup, shut the VM down, take a backup, delete the VM, create a new shell, restore the VM, and don't take another snapshot again. ;)

EDIT: Obviously that delete includes the VHDX/AVHDX files associated.


Thanks, Philip... but I'm still left with a few questions:

1.  Can I compact the existing AVHDX file?

2.  This will expose my noobiness:  It seems to me that the "level" called "Now" in my picture would represent the CURRENT status of our VM... and that if we delete the entry dated 2018, then we're just deleting the ability to revert back to that point in time.  Yes?  No?

You could also create another checkpoint and export it onto external drive
- Most likely to be bigger than the original
Mount it from external drive for testing, if ok
Delete the Virtual machine and recreate from scratch, mounting the exported VHD back.
- Otherwise it creates the checkpoints again..

Deleting the Checkpoint is merging the changes up one level.
Applying the checkpoint is discarding the changes, going back in time

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Technical Architect - HA/Compute/Storage
1: Parent is not the problem. The differencing disk is. All of the changes made in the OS/Data since the snapshot/checkpoint was taken is stored in that one huge file. There is no compacting that.

2: As already mentioned, deleting the existing snapshot/checkpoint in Hyper-V Manager will initiate a MERGE. That process requires enough free space to create a whole new parent VHDX file. Obviously, there is not enough free space to do so. Do not delete that snapshot/checkpoint. That will create no end of heartache.

I'm not sure an export to another machine somewhere on the network would work since there's no space left at all.

The only real option, and quickest for that matter, is the delete and restore from backup method.
Backup & restore would be quicker, if you have a good software/strategy.

Otherwise buy an external USB3 (the server might not support, but you could also buy USB3 card and install prior). 4TB is plenty and costs bugger all. Done it before.



Thank you all.

For the next few hours/ day, in order to "stop the bleeding" and prevent even more disk space from being taken up, should we turn off "Enable checkpoints?"  If we do that, will it damage the VM if we do nothing else?   (See attached.)

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