Information Technology Reference
In-Depth Information
Reverting to a Snapshot
Reverting to a snapshot incurs a loss of data. Any data that was written since the snapshot has
occurred will no longer be available, along with any applications that were installed since the
snapshot was taken. h erefore, revert to snapshots only if you have determined that the loss of
data is acceptable or if the data is backed up elsewhere.
Figure 9.32
h e same VM, after
reverting to a snap-
shot taken before
the temporary fold-
ers were created,
no longer has any
record of the data.
As you can see, snapshots are a great way to protect yourself from unwanted changes to
the
data
stored in a VM. Snapshots aren't backups and should not be used in place of backups.
However, they can protect you from misbehaving application installations or other processes
that might result in data loss or corruption.
There are additional VM management tasks that we'll discuss in other chapters. For
example, you might want to migrate a VM from one ESXi host to another ESXi host using vMo-
tion; this is covered in Chapter 12. Changing a VM's resource allocation settings is covered in
Chapter 11.
In the next chapter, we'll move from creating and managing VMs to streamlining the
VM provisioning process with templates, OVF templates, and vApps. While VMware makes
the VM provisioning process pretty easy, we'll show you how using templates can simplify
server provisioning even more while bringing some consistency to your VM and guest OS
deployments.
h
e Bottom Line
Create a virtual machine.
A VM is a collection of virtual hardware pieces, like a physi-
cal system—one or more virtual CPUs, RAM, video card, SCSI devices, IDE devices, l oppy
drives, parallel and serial ports, and network adapters. This virtual hardware is virtualized
and abstracted from the underlying physical hardware, providing portability to the VM.
Master It
Create two VMs, one intended to run Windows Server 2012 and a second in-
tended to run SLES 11 (64-bit). Make a list of the differences in the coni guration that are
suggested by the Create New Virtual Machine Wizard.
Install a guest operating system.
Just as a physical machine needs an operating system,
a VM also needs an operating system. vSphere supports a broad range of 32-bit and 64-bit
operating systems, including all major versions of Windows Server, Windows 7, Windows XP,
and Windows 2000 as well as various l avors of Linux, FreeBSD, Novell NetWare, and Solaris.
Master It
What are the three ways in which a guest OS can access data on a CD/DVD,
and what are the advantages of each approach?
