6.8. Using Virtual Machine Snapshots

A snapshot is a view of a virtual machine's operating system and all its applications at a given point in time. The snapshot is a very important tool in managing virtual machines. Whenever the virtual machine is powered off, you can create a snapshot of a virtual machine's hard drive. If future changes cause a problem, you can restore the virtual machine to the previous state of any of the snapshots. Restoration to a snapshot means that you return to the point in time when the snapshot was created. After you restore to that point of time, you cannot return to snapshots created after that time.
For example, given that snapshots were created on Sunday at 8 am, 10 am, 12 pm, and at 3 pm. At 6 pm, a problem arises on your virtual machine, and you decide to restore the virtual machine to the state of the snapshot created at 10 am. This restore automatically erases the snapshots created after 10 am, meaning the snapshots of 12 pm and 3 pm no longer exist. However, the snapshots taken before the restoration, in this case at 8 am, still exist.

Warning

When a restoration is performed from a snapshot, all data written to the virtual machine’s hard drive after the selected snapshot creation point is lost, including subsequent snapshots.

6.8.1. Creating Snapshots of Virtual Machines

This section describes how to create a snapshot of a virtual machine. You can also Preview, Commit, Undo and Delete the snapshot.

To create a snapshot of a virtual machine:

  1. Click the Virtual Machines tab.
  2. If the virtual machine for which you want to create a Snapshot is not displayed, perform a search (see Section 1.2, “Search”).
  3. Select the virtual machine. Ensure that the virtual machine has a status of Down.
  4. On the Details pane, select the Snapshots tab. Click the Create button.
    The Virtual Machines Details Pane with Snapshots tab

    Figure 6.14. The Virtual Machines Details Pane with Snapshots tab


    The Create Snapshot dialog box displays.
  5. Enter a description for the snapshot, select all the virtual disks attached to the virtual machine and click OK.
    New Snapshot Dialog Box

    Figure 6.15. New Snapshot Dialog Box


    The virtual machine's operating system and applications are stored in a snapshot that can be previewed or restored. The status of the virtual machine briefly changes to Image Locked, before returning to Down.