You can read this from this or watch a video
This site is about FAQ of Hyper-V Snapshots describing what snapshot is and what effects we have while snapshotting.
As we aleady know, snapshot is to use for saving vm at a certain time like making ghost images.
It provides simle way to backing VM up in a very short time.
However, it has also demerit. the killer part is that your stoage could happen shortage problem.
After snaphot is deleted, snapshot files wouldn't be deleted if you don't shut down the VM or put it into saved status.
I have a VM which took two snaphots in VMM console.
And this is snaphot files on the hard disk. (1 original VHD and 2 avhd)
Snapshot file has *.ahvd
Among files, I try to remove this one.
This snaphot file is to be deleted on HardDisk.
the snapshot was deleted !!!
But, As you can see, the snapshot file haven't been deleted on hard disk.
Let's me the VM change into Saved status.
I'm going to put it into Shutdown or Saved in VMM
the snapshot file was finally deleted.
Keeps in mind that deleting time on hard disk is depend on the size of the snapshot file or
how many snapshot was kept.
There are other points:
- Do not delete .avhd files directly from the storage location. Instead, use Hyper-V Manager to select the virtual machine, and then delete the snapshots from the snapshot tree
- Do not expand a virtual hard disk when it is used in a virtual machine that has snapshots. Doing so will make the snapshots unusable
It's important to know this kind of mechanism. When you bakup your system up, you don't want to shut the system down. at this point of view, snapshot isn't proper backup solution.