The virtual machine (VM) snapshot is one of the first features that totally hooked me on virtualization. It allowed me to quickly mark my spot to provide a repeatable environment for testing. I still use virtualization for testing today, as well as production.
The VM snapshot still plays a critical role for VM admins today with Hyper-V and Windows Server 2012. A snapshot (or checkpoint as it is called in System Center Virtual Machine Manager) is simply a point-in-time view of the VM to which the state can be rolled back, if needed. Think of it like playing a log file in reverse to go back in time to the VM.
By default, a VM created on Hyper-V will create the snapshot on a VM and put the associated snapshot files in a designated path on the C:\ drive. Should a lot of snapshots and VMs be in use, it may be worth ensuring that each Hyper-V VM has their associated snapshots on a designated location. This can be a larger volume or possibly a slower volume (with the thought being not to allocate premium storage for VM snapshots). Figure A below shows where the Hyper-V VM properties allow the configuration of the snapshot file location.
Figure A
Click to enlarge.
When a snapshot exists, a temporary path will be created in the selected path named \Snapshots and then an additional folder with a hexadecimal string will be created along with a number of temporary files (.BIN, .XML, .VSV and possibly more). Using snapshots is a great feature of virtualization, but be advised that they alone are not a backup of a VM. The source .VHD or .VHDX file integrity needs to be maintained for snapshots to be effective.
Do you redirect snapshots for Hyper-V VMs? If so, where do you put them and what is your logic? Share your comments below.
