10 Ways to Save with Desktop Virtualization

Author: John Hales, Global Knowledge VMware instructor, A+, Network+, MCSE, MCDBA, MCT, VCP, VCI, EMCSA

Abstract

View is VMware's VDI (Virtual Desktop Infrastructure) tool that makes virtual Windows XP, Vista, and/or 7 desktop VMs accessible through a common interface, across the LAN or WAN, focusing on the money-saving aspects of VDI.

Sample

Introduction

Server virtualization is a mature technology that has been deployed in many companies of all sizes and has proved its value time and time again. Using the same concepts and thinking, a few years ago people started considering desktop virtualization, expecting the same kind of benefits. Desktop virtualization and server virtualization are two different use cases with different costs and benefits, though they may use the same technology to accomplish the actual virtualization of desktops or servers.

The purpose of this white paper is not to discuss what desktop virtualization is (in much detail anyway), how it differs from server virtualization, the pros and cons of it, etc. Rather, this paper is designed to review how desktop virtualization can save you money. Some of these points will be more applicable to one situation, company, etc., than another, but the idea is to stimulate and encourage thought about the technology and its use.

For the purposes of this white paper, desktop virtualization is discussed in the context of VMware vSphere and VMware View, though many of the concepts apply to other desktop and/or server virtualization platforms as well.

Using vSphere

vSphere is VMware's bare-metal hypervisor and consists of two platform choices as follows:

• ESX, which has been around for many years and includes a service console for command line access at the server, but which VMware has announced is being discontinued (version 4.1 is the last version).
• ESXi, which was introduced with ESX 3.5 and does away with the Linux-based command line on the server (though command line access is still provided remotely and a minimalist command line is provided for troubleshooting issues on the server) and represents the future.

Neither product will be discussed in detail here, but as vSphere provides the foundation for View, some of the key features and functions will be provided to create a frame of reference.

The review of key functions and components is based on the diagram below.

vSphere was built to be used with an internal cloud (servers, storage, and networking all on-site at the customer's location) and/or with an external cloud (servers, storage, and networking all provided by companies on the Internet that may or may not integrate with any local infrastructure). Both ESX and ESXi, hereafter denoted generically as ESX(i), provide the same feature set when licensed and managed by vCenter. vCenter is VMware's management product that provides simple graphical, command line, and/or API (Application Programming Interface) access to functionality, some of which ESX(i) provides and some of which vCenter provides.

Entire books are written and many classes exist that go into the capabilities in great detail, but for our purposes, some of the keys ones are:

• VMFS: This is the native file system in ESX, similar to NTFS for Windows or ext2 for Linux. It is a clustered file system, meaning that it was designed to be shared by multiple servers at the same time. It was designed to store and access VMs efficiently. It also supports thin provisioning, where the VM sees the entire space allocated to it, but only consumes as much space as it needs. This functionality will be important when linked clones are discussed later in this paper.
• Standard Switch: This virtual switch is the virtual link between the virtual NICs in the VMs and the physical NICs (and thus the outside world). It is basically a software implementation of a physical switch. They have been used since the start of VMware and still exist today.
• Distributed Switches: Introduced with vSphere, they centralize configuration and management of the switch in vCenter and the specific configuration is then pushed out to all servers that are associated with the switch. This provides much greater scalability and simplifies management, but is only available in the Enterprise Plus version of ESX(i) and vCenter.
• Hot Add: This functionality is similar to the functionality in the physical world and allows components, such as network cards and hard drives to be plugged in while the VM is running (assuming the underlying OS can dynamically see and use the changes). Some operating systems also support the ability to hot add RAM and even CPUs. Note that the capability exists only to add, not to remove, components. To remove a component, the VM must be powered off first.