There are two main types of snapshot:
- An internal snapshot: The base image file itself contains the saved state and all subsequent changes to the virtual machine
- An external snapshot: The base image will contain the saved state of the virtual machine thus becoming a read-only base image, and a new overlay image is created to track any future changes
Both types of snapshots can be performed on just the disk or the memory of the virtual machine, either on a live or stopped instance.
In the preceding step 1, we create an internal snapshot of the virtual machine. After the snapshot, there's only one image file: the original image, now containing the snapshot. We can see that the image is a snapshot in step 4, under the Snapshot ...