Using virtual appliances and desktop virtualisation


Using virtual appliances and desktop virtualisation

In his Webtorial report 2010 Virtualisation: Benefits, Challenges and Solutions, analyst Jim Metzler of Ashton Metzler & Associates outlines the benefits and challenges of virtualising IT components even beyond servers. Specifically, Metzler reports on virtual server management, virtual WAN optimisation controllers (WOCs) and application delivery controllers (ADCs) as virtual appliances, as well as methods of desktop virtualisation implementation. In this report summary, learn the reasons for using WAN optimisation and application delivery controllers as virtual appliances and how to overcome some desktop virtualisation challenges.

Virtual appliances: WAN optimisation and application delivery controllers

A virtual appliance is based on network appliance software running in a virtual machine (VM). Virtual appliances can include, among other tools,  WAN Optimisation Controllers (WOCs), Application Delivery Controllers (ADCs), firewalls, and  performance monitoring solutions.

Important synergies exist among virtual servers, virtual desktops and virtual appliances such as a WOC or a performance monitoring solution. Perhaps the most important synergy is that virtual appliances are of particular interest to IT organisations when server virtualisation technology has already been disseminated to branch offices and has also been implemented in the data centre.

More resources on Application Delivery Controllers
Next generation application delivery controllers have come a long way from becoming virtual appliances themselves to optimising application delivery in a virtual environment.

Can application delivery controllers support virtualisation?

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Network management and application delivery controllers

In the branch office, a suitably placed virtualised server could potentially host a virtual WOC appliance as well as other virtual appliances. Alternatively, a router or a WOC that supports VMs could also serve as the infrastructure foundation of the branch office. Virtual appliances can therefore support branch office server consolidation strategies by enabling a single device to perform multiple functions typically performed by multiple physical devices.

Application delivery controllers as virtual appliances

A virtualised ADC makes it easy for an IT organisation to package and deploy a complete application – resulting in more focused control and management options. When an entire application resides on VMs inside a physical server, for example, the virtualised ADC that supports the application resides in the same physical server and is tuned for the particular application. This makes it easy to replicate or migrate that application as needed. It also means that the ADC could be either under the control of a central IT group or the group that supports that particular application. In the latter situation, when the application group takes action relative to the ADC, it will affect only its specific application.

Cost advantages of virtual appliances

Software-based virtual appliances can cost notably less than hardware-based appliances with the same functionality. In addition, a software-based solution can potentially leverage the functionality provided by the hypervisor management system to provide a highly available system without the need to pay for a second appliance.

Also, if virtualised appliances have been deployed, it is easier for various networking functions to be migrated along with VMs in order to replicate the VM's networking environment in its new location.

Integrating virtual appliances with VM management

When evaluating the deployment of virtual appliances in a dynamic environment, it is crucial to consider the degree of integration of the virtual appliance with the virtual server management system. Ideally this management system would recognise the virtual appliances as another type of VM and understand associations between appliance VMs and application VMs in order to allow a coordinated migration when desirable.

Desktop virtualisation implementation

More resources on desktop virtualisation
Networking for desktop virtualisation poses many new considerations for network admins and architects.

Desktop virtualisation network requirements

Desktop virtualisation network challenges

Desktop virtualisation storage strategies

 Half of all IT organisations have already implemented at least some desktop virtualisation; and within a year, roughly 75% of IT organisations will have implemented it. Desktop virtualisation is driven by a combination of cost savings, increased ability to comply with myriad regulations, and improved data and application security. The two fundamental forms of desktop virtualisation are:

  • Server-side application/desktop virtualisation
  • Client-side application/desktop virtualisation

With server-side virtualisation, the client device plays the familiar role of a terminal accessing an application or desktop hosted on a central presentation server. There are two primary approaches to server-side application/desktop virtualisation. They are:

  • Server-based computing (SBC)
  • Virtual desktop infrastructure (VDI)

Client-side application virtualisation is based on a model in which applications are streamed on-demand from central servers to client devices. On the client side, streamed applications are isolated from the rest of the client system by an abstraction layer inserted between the application and the local operating system.

Desktop virtualisation challenges

One of the primary desktop virtualisation challenges is achieving an acceptable user experience for client-to-server connections over a WAN. For example, VDI requires at least 200 Kbps of bandwidth per simultaneous user, and the minimum peak bandwidth required for a PCoIP connection is one Mbps. In most cases, the successful deployment of desktop virtualisation means implementing WAN optimisation techniques that focus on the particular characteristics of the traffic that are associated with desktop virtualisation.

To learn more about challenges associated with virtualisation, as well as the emerging solutions that may be of use to IT organisations, see Metzler's 30-page Webtorial report 2010 Virtualisation: Benefits, Challenges and Solutions.

About the author: Dr. Jim Metzler, Principal at Ashton Metzler and Associates, is a widely recognised authority on both network technology and its business applications. In more than 28 years of professional experience, Jim has helped numerous vendors refine their product and service strategies and has helped enterprises evolve their network infrastructure. He has directed and conducted market research at a major industry analyst firm and has run a consulting organisation. Jim holds a Ph.D. in numerical analysis from Boston University. He has co-authored a book, published by Prentice Hall, entitled Layer 3 Switching: A Guide for IT Professionals.

This was first published in January 2011

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