Why does Hyper-V create a snapshot every time I apply a snapshot?
I was asked this question today. My first response was: “It doesn’t”. But after a bit of thought I realized what was going on for the user in question. Whenever you take a snapshot of a Hyper-V virtual machine, we capture the point in time data about that virtual machine and then continue to run. When you later apply that snapshot to the virtual machine – we will throw away any data that has not been captured in a virtual machine snapshot.
Imagine the following workflow:
- You create a virtual machine
- You install Windows and some applications
- You take a virtual machine snapshot
- You write your opus magnum inside the virtual machine
- You apply the snapshot taken in step three
You have now lost your opus magnum, and life no longer has any meaning for you (okay – I might be exaggerating here – but you have lost some data). Hopefully, the consequences here are obvious to the user. But in case they are not – we provide the following option:
When you apply a snapshot we ask you if you want us to take a new snapshot first – to capture any data that is in the present virtual machine. Seems reasonable – right? In this case the user must have checked the option to “don’t ask me again” without actually reading the text. Now, every time that they take a snapshot – we create a new one to capture any potential data changes. Hence the question in the title.
Luckily, this is simple to correct.
If you open the Hyper-V Settings and go all the way to the bottom of the list – you will see an option labeled Reset Check Boxes. Go here and click the button – we will then clear every time you checked “don’t ask me again” and you will get all the default prompts and questions:
On a side note – and I know that I am criticizing myself here – it always bugs me when software has a “don’t ask me again” option on a dialog with multiple choices. I never actually check the box here, because I can never be certain about what the outcome of checking the box will be (what will the software default to?). This is something that I would like to see us handle better in the future.
Cheers,
Ben