action. What happens when you delete a checkpoint depends on where it is in the
hierarchy of checkpoints and where the current Now state of the virtual machine is. If
you delete a checkpoint that is on a different branch from the Now state and has no
child checkpoints, its differencing virtual hard disk will be deleted along with any state
and configuration files. If you delete a checkpoint that is part of the Now branch or
has child checkpoints, its state files will be deleted but the contents of its differencing
virtual hard disk will be merged into its child object, which could be the Now state or
another checkpoint. There is an exception. If you delete a checkpoint that has multiple
child snapshots, the differencing virtual hard disk is kept; to remove it would require
its content to be merged into each child virtual hard disk, which would use up
additional space, and that’s likely not the experience administrators would expect.
Although the way in which a checkpoint deletion is handled differs, what is consistent
is that the checkpoint is no longer usable.
You may wonder how you get different branches of checkpoints. The key is that you
can apply a specific checkpoint and then create new checkpoints from that point. This
would create different branches, as shown in Figure 6.7. If you perform a Revert
action on a virtual machine, you will be prompted to create a new checkpoint of the
current state of the virtual machine to avoid losing its state.