Information Technology Reference
In-Depth Information
consistent. This can help ensure that the data within the guest i le system is intact in the
snapshot.
When a snapshot is taken, depending on the previous options, some additional i les are cre-
ated on the datastore, as shown in Figure 9.29.
Figure 9.29
When a snapshot
is taken, some
additional fi les are
created on the VM's
datastore.
It is a common misconception for administrators to think of snapshots as full copies of VM
i les. As you can clearly see in Figure 9.29, a snapshot is not a full copy of a VM. VMware's snap-
shot technology consumes minimal space while still reverting to a previous snapshot by allocat-
ing only enough space to store the changes rather than making a full copy.
To demonstrate snapshot technology and illustrate its behavior (for practice only), we per-
formed the following steps:
1.
We created a VM with a default installation of Windows Server 2012 with a single hard
drive (recognized by the guest OS as drive C:). The virtual hard drive was thin provi-
sioned on a VMFS volume with a maximum size of 40 GB.
2.
We took a snapshot named FirstSnap.
3.
We added approximately 3 GB of data to drive C:, represented as win2k12-01.vmdk.
4.
We took a second snapshot named SecondSnap.
5.
We once again added approximately 3 GB of data to drive C:, represented as
win2k12-01.vmdk.
Review Table 9.2 for the results we recorded after each step. Note that these results were
recorded as part of our example and may differ from your results if you perform a similar test.
