Use Virtualization in Windows Server 2012 - MCSA Windows Server 2012 R2: Installation and Configuration Study Guide - page 455

Fixed size The size of the VHD file is fixed to the

size specified when the disk is created.
This option is faster than a dynamically
expanding disk. However, a fixed-size
disk uses up the maximum defined space
immediately. This type is ideal for cloning
a local hard drive.

A fixed-size disk provides
faster access than dynami-
cally expanding or differenc-
ing disks, but it is slower than
a physical disk.

Differencing This type of disk is associated in a parent-

child relationship with another disk. The
differencing disk is the child, and the
associated virtual disk is the parent. Dif-
ferencing disks include only the differ-
ences to the parent disk. By using this
type, you can save a lot of disk space
in similar virtual machines. This option
is suitable if you have multiple virtual
machines with similar operating systems.

Differencing disks are most
commonly found in test envi-
ronments and should not be
used in production environ-
ments.

Physical (or
pass-through
disk)

The virtual machine receives direct pass-
through access to the physical disk for
exclusive use. This type provides the
highest performance of all disk types and
thus should be used for production serv-
ers where performance is the top priority.
The drive is not available for other guest
systems.

This type is used in high-end
datacenters to provide opti-
mum performance for VMs.
It's also used in failover clus-
ter environments.

Creating Virtual Hard Disks
To help you gain practice in creating virtual hard disks, the following three exercises will
teach you how to create a differencing hard disk, how to clone an existing disk by creating
a new disk, and how to configure a physical or pass-through disk to your virtual machine.
First, in Exercise 9.3, you will learn how to create a differencing virtual hard disk.

exerciSe 9.3

creating a differencing hard disk

1. Open Hyper-V Manager.

2.

In Hyper-V Manager, on the Actions pane, choose New ➢ Hard Disk.

3. In the New Virtual Hard Disk Wizard, click Next on the Before You Begin page.