Introduction to Virtualization


Virtualization can be categorized into two key focus areas, the data center and desktop, and residing under a single management platform.

  • Server OS virtualization
  • Datacenter Virtualization
  • Desktop virtualization
  • Application virtualization
  • Remote Desktop Services
        • (session virtualization and the Virtual Desktop Infrastructure (VDI))

The challenges of managing a desktop are that you want to minimize IT cost and complexity while creating an inclusive enterprise wide management strategy that addresses the virtualization of data and user settings, apps, and operating systems.

Virtualization Graphic 1

Server OS

Server OS virtualization is the first element of Microsoft’s virtualization solution. With server OS virtualization, separate OS are consolidated on a single server, allowing users to run multiple OS on the same physical hardware. This was a real game changer and saw real advantages in hardware consolidation and optimization of server resources. This is enabled by the Hypervisor – which runs directly on the host hardware to control the hardware and to monitor guest operating-systems. A guest OS runs on another level above the hypervisor.

[Ref: Goldberg, (February 1973) (PDF). Architectural Principles for Virtual Computer Systems. Harvard University. pp. 22–26.]

Typical Set upServer Virtualization Graphic 

App Virtualization

Instead of isolating the operating system (OS) from the hardware, application virtualization isolates the application from the OS. While to the user, this doesn’t really differ from the traditional concept of directly installing applications directly on the OS, to IT organizations the difference can be massive. App Virtualization (Microsoft App-V) multiple versions of the same application can run on one computer system at the same time. Also, apps can be automatically streamed to a desktop, on demand and as needed, without having to be installed by a local IT tech. App-V can provide centralized application management and security and easy, fast patching and upgrades. It is available as part of Microsoft Desktop Optimization Pack (MDOP).

App Virtualization Graphic

“No more Patch Tuesday”

Isolation in this scenario occurs one level up in the stack from the OS and hardware. App virtualization isolates an application and all of that application’s files and resources from the operating system (OS) , and any other application on the system.

This technology can address a number of headaches. First, because the application is isolated from the OS, there’s no need for the application to be installed in any traditional sense of the word. (This means multiple versions of the same application can run on a single desktop) This also means that applications can be streamed out to a desktop when the user needs them, which doesn’t require a helpdesk call or a IT visit to the desk.

For the average desktop admin, this drastically reduces the time and cost implications of desktop management because it brings patch and upgrade management to one central location and will accelerate the deployment of any new applications. It also ensures the entire desktop environment is configured to be secure and consistent.

This enables the mobile end user, as the work critical apps they need to do their jobs actually follow them around the organization (Roaming Users). Interestingly, Microsoft’s application virtualization solution, App-V, can also stream only the parts of the application needed by the user and have instant click start-ups

Once the user logs off, the application can be removed, and is no longer there risking access by a non-authorised or unlicensed user.

Session Virtualization

This was originally Terminal Services and is used by several million users. Microsoft combined with Citrix have a pre-dominant share of the market. Microsoft have now named this Remote Desktop Services (RDS). This comes as part of Windows Server 2008 R2

Session virtualization isolates the processing of the operating system and applications from the graphics and the Input and Output devices (keyboard and mouse). Once isolated, session virtualization sends the graphics from a central server and application out to an accessing device where the end user sees the display in real time. It is just as if the user were watching a live feed. However, session virtualization also captures the keyboard and mouse events of the remote user and replays them on the central datacenter.

Server Virtualization Graphic 3

This allows a user to instantly interact with the remote system. This design makes the user feel like the OS and application are actually running on the device in front of them, even though the application is sourced from a central datacenter.

This has real benefits in security with better security having all data stored and managed centrally. In this scenario, there is one shared copy of the software on the server, and this also has cost savings for patching and updates. Also, with data security and privacy concerns, having a central database provides a layer of security, by ensuring copies of the main database never leave the data center.

Virtual desktop infrastructure (VDI)

This is the most complex component. At its core, VDI uses the same technology as server virtualization and creates a separate OS environment on the desktop, called a virtual machine (VM). This will often be executed on the server.

VDI Graphic

In Session Virtualization (Remote Desktop Services) users access a Windows Server OS hosting their application – In VDI, a Windows desktop hosts the application.
In Session Virtualization, only one copy of the OS is run on the hardware, and multiple users share that OS to run the application.

In VDI, each user is assigned their own complete OS, which is then used to host whatever apps the user needs

The VM is then copied to a server farm in a data center, with each server in the farm running dozens of desktop VMs. Of course, a desktop OS is intended to be used with end users, so these virtual desktops are then accessed remotely by the end users using the same remote access technology we just talked about on the session virtualization (Remote Desktop Services)

This means that on average, VDI is more flexible and customizable than session virtualization. It is also less effective and more expensive to implement. In fact, due to licensing restrictions, VDI can be a lot more expensive than session virtualization for most customers.

What is the Microsoft product stack?

Virtualization Stack

Windows Server 2008 R2 and Hyper-V

Microsoft have built Hyper-V straight into the Windows Server 2008 R2. Hyper-V is Microsoft’s answer to the hypervisor, and provides the layer of abstraction between the virtual OS and the base hardware.

Hyper-V R2 now provides the ability to move live workloads between different physical servers without disrupting the end users. This is a feature Microsoft call live migration and effectively matches Vmotion by VMware.


Microsoft also provide an end-to-end management of applications, operating systems, and hardware in both physical and virtual deployments. In addition, they have also responded to the market dominance of VMware by supporting management of ESX hosts.

Virtualization Graphic  

System Center Suite
  1. System Center Operations Manager (SCOM) ascertain risk of the IT environment and enables quick response to disruptive events.
  2. System Center Configuration Manager (SCCM) provides system deployment, task automation, compliance management, and policy-based security management.
  3. System Center Data Protection Manager (SCDMP) provides continuous data protection for Microsoft applications and file servers, so that IT administrators and users can quickly and easily recover data
  4. System Center Virtual Machine Manager (SCVMM) provides a centralized place for organizations to view and manage their virtual machines across both Hyper-V and VMware ESX farms.


Virtual Machine Manager

Through one console, VMM allows administrators to manage and monitor virtual machines and hosts to ensure they are meeting the needs of the corresponding business groups. In response to VMware – VMM now manages VMware ESX virtualized infrastructure in conjunction with the Virtual Center product. Now administrators running multiple virtualization platforms can rely on one tool to manage everything. With its compatibility with VMware VI3 (through Virtual Center), VMM now supports features such as VMotion and can also provide VMM-specific features like Intelligent Placement to VMware servers. Similarly, VMM also provides a straightforward wizard that can convert VMware virtual machines to VHDs through Virtual-to-Virtual (V2V) transfer process. VMM also supports snap conversion of physical to virtual machines.


One thought on “Introduction to Virtualization

  1. Pingback: The roundup: here’s what you may have missed « Microsoft License Review

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