Hyper-V Program Manager
There have been a lot of questions about how Hyper-V virtual machine snapshots work, and what considerations you need to take when using them.
Frankly this is an area where I need to do more blogging – and we need to work to make the technology easier to understand “out of the box”. However – in the mean time our documentation team has put together a handy Hyper-V virtual machine snapshot FAQ that you can read here:
This details things like: How are snapshots stored? What considerations do you need to be aware of? Why is my virtual machine going into “paused-critical” state? and more.
I noticed that it doesn't take long to perform a delete snapshot action from the SCVMM GUI, even though the Hyper-V mmc still shows merging in progress. Seems like SCVMM allows user to interact with the VM before merging is completed. So new user requests such as starting up the VM, or creating a new snapshot would post any risk to the VM?
Also, snapshots based on fixed vhd files basically lock away all that free space that has been pre-provisioned inside the fixed vhd. Snapshots are dynamically expanding by nature and running a fixed-vhd VM on a snapshot for a long time means you lose the performance benefits of fixed vhd files. Once you are happy to commit the data in the snapshot do so without delay, especially for production systems.