Using Snapshots to Preserve Virtual Machine States
A snapshot includes the contents of the virtual machine memory, virtual machine settings, and the state of all
the virtual disks. When you revert to a snapshot, you return the memory, settings, and virtual disks of the
virtual machine to the state they were in when you took the snapshot.
You might want to take snapshots in a linear process if you plan to make changes in a virtual machine. For
example, you can take a snapshot, continue to use the virtual machine from that point, take another snapshot
at a later point, and so on. You can revert to the snapshot of a previous known working state of the project if
the changes do not work as expected.
For local virtual machines, you can take more than 100 snapshots for each linear process. For shared and remote
virtual machines, you can take a maximum of 31 snapshots for each linear process.
If you are testing software, you might want to save multiple snapshots as branches from a single baseline in a
process tree. For example, you can take a snapshot before installing different versions of an application to make
sure that each installation begins from an identical baseline.
Chapter 4 Using Virtual Machines
VMware, Inc.
65
Figure 4-1.
Snapshots as Restoration Points in a Process Tree
Windows
operating
system
baseline
IE base
Firefox base
SP1
IE base1
You Are
Here
Firefox base1
SP2
IE base2
Firefox base2
Multiple snapshots have a parent-child relationship. The parent snapshot of a virtual machine is the snapshot
on which the current state is based. After you take a snapshot, that stored state is the parent snapshot of the
virtual machine. If you revert to an earlier snapshot, the earlier snapshot becomes the parent snapshot of the
virtual machine.
In a linear process, each snapshot has one parent and one child, except for the last snapshot, which has no
children. In a process tree, each snapshot has one parent, one snapshot can have more than one child, and
many snapshots have no children.
Using the Snapshot Manager
You can review all snapshots for a virtual machine and act on them directly in the snapshot manager.
You must use the snapshot manager to perform the following tasks.
n
Show AutoProtect snapshots in the
Snapshot
menu.
n
Prevent an AutoProtect snapshot from being deleted.
n
Rename a snapshot or change its description.
n
Delete a snapshot.
All other snapshot actions are available as menu items in the
Snapshot
menu under the
VM
menu.
When you open the snapshot manager for a virtual machine, the snapshot tree appears. The snapshot tree
shows all of the snapshots for the virtual machine and the relationships between the snapshots.
The
You Are Here
icon in the snapshot tree shows the current state of the virtual machine. The other icons that
appear in the snapshot tree represent AutoProtect snapshots, snapshots of powered-on virtual machines,
snapshots of powered-off virtual machines, and snapshots that are used to create linked clones.
