Windows Server 2008 : Planning Operating System Virtualization (part 1)

7/13/2011 5:48:22 PM
In this article, you will learn how to design an operating system virtualization strategy. This includes learning how to assess which existing server deployments make good candidates for virtualization, learning how to plan the migration of servers from traditional hardware-based installations to virtual hosts, and learning the most effective locations in an existing network infrastructure to deploy servers that host virtual machines (VMs). This lesson not only explains Hyper-V but also examines Virtual Server 2005 R2 and System Center Virtual Machine Manager 2007. To effectively design an operating system virtualization strategy, you need to understand how these separate components can be integrated to meet your organization’s needs.

Every year the hardware that vendors make available becomes more powerful. Increasingly powerful hardware changes the way that enterprise administrators plan the deployment of server resources. Whereas, in the past, server utilization patterns and performance meant that only a single server role or application could be deployed on computer hardware, today’s server hardware can cope with a much higher workload. This means that fewer servers are required to do the same amount of work. Virtualization allows you to fully utilize the increased computing power made available by modern hardware without worrying about the conflicts that might occur if you cohosted important applications and server roles on a single instance of Windows Server 2008. Virtualization provides the following benefits over traditional installations:

  • More efficient use of hardware resources Services such as Dynamic Host Configuration Protocol (DHCP) and Domain Name System (DNS), although vital to network infrastructure, are unlikely to push the limits of your server’s processor and RAM. Although it is possible to co-locate the DNS and DHCP roles on the one Windows Server 2008 computer, the strategy of separating network roles onto separate partitions allows you to relocate those partitions to other host computers if the circumstances and usage of those roles change.

  • Improved availability Consolidating these services onto a single hardware platform can reduce costs and maintenance expenses. Although moving from many platforms to one might look like it would lead to a single point of failure, implementing redundancy technologies (clustering and hot-swappable hardware such as processors, RAM, power supplies, and hard disk drives) provides a greater level of reliability for lower cost. Consider the following situation: four Windows Server 2008 computers are each running a separate application provided to users on your network. If a hardware component fails on one of those servers, the application that the server provides to users of the network is unavailable until the component is replaced. Building one server with redundant components is cheaper than building four servers with redundant components. If a component fails, the built-in redundancy allows all server roles to remain available.

  • Servers need to be only intermittently available Some servers need to be available only intermittently. For example, the best practice with a root CA is to use subordinate CAs to issue certificates and to keep the root CA offline. With virtualization, you could keep the entire virtualized root CA server on a removable USB hard disk drive in a safe, only turning it on when necessary and thereby ensuring the security of your certificate infrastructure. Virtualization frees up existing hardware that is rarely used—or makes it unnecessary to buy it.

  • Role sandboxing Sandboxing is a term used to describe the partitioning of server resources so that an application or service does not influence other components on the server. Without sandboxing, a failing server application or role has the capacity to bring down an entire server. Just as Web application pools in Internet Information Services (IIS) sandbox Web applications so that the failure of one application will not bring all of them down, running server applications and roles in their own separate virtualized environment ensures that one errant process does not bring down everything else.

  • Greater capacity Adding significant hardware capacity to a single server is cheaper than adding incremental hardware upgrades to many servers. You can increase capacity by adding processors and RAM to the host server and then allocating those resources to a virtual server as the need arises.

  • Greater portability After a server has been virtualized, moving it to another host if the original host’s resources become overwhelmed is relatively simple. For example, suppose that the disks on a Windows Server 2008 Enterprise computer hosting 10 virtualized servers are reaching their input/output (I/O) capacity. Moving some of the virtualized servers to another host is simpler than migrating or upgrading a server. Tools such as System Center Virtual Machine Manager, make the process even simpler.

  • Easier backup and restore Tools such as volume shadow copy allow you to back up an entire server’s image while the server is still operational. If a host computer fails, the images can be rapidly restored on another host computer. Rather than backing up individual files and folders, you can back up the entire virtualized computer in one operation. System Center Virtual Machine Manager (SCVMM) 2007 allows you to move VMs back and forth to the Storage Area Network (SAN) and even migrate VMs between host computers. SCVMM 2007 is covered in more detail later in the lesson.

Virtual Server 2005 R2

Virtual Server 2005 R2 SP1 is a product that you can download and install for free from Microsoft’s Web site. Virtual Server 2005 R2 SP1 allows you to host and manage VM instances on a 32-bit version of Windows Server 2008. You can also install Virtual Server 2005 R2 SP1 on the 32-bit and 64-bit versions of Windows Server 2003 SP1/R2. It is also possible to install Virtual Server 2005 R2 SP1 on Windows Small Business Server 2003 and Windows XP Professional, though you should never use Windows XP Professional as a virtual host for virtualized servers that are used in a production environment. Virtual Server 2005 R2 SP1 cannot be installed on a Windows Server 2008 computer that has been installed using the Server Core option.

More Info: Downloading Virtual Server 2005 R2

You can download a free copy of Virtual Server 2005 R2 by accessing the following address on Microsoft’s Web site:

When planning an operating system virtualization strategy, you should consider Virtual Server 2005 R2 SP1 when the computer that you plan to use as a virtual host has a 32-bit, as opposed to a 64-bit, processor. This is because Hyper-V, which is covered later in this lesson, is a Windows Server 2008 feature that is available only on 64-bit versions of Windows Server 2008. For example, say that your organization has a computer with Windows Server 2003 Enterprise installed. The computer has eight processors and 64 GB of RAM, but the processors on the computer are 32-bit rather than 64-bit. Computers with large amounts of RAM make excellent VM hosts, but because the processors on the computer have a 32-bit rather than a 64-bit architecture, it is impossible to install the 64-bit version of Windows Server 2008 on this computer and impossible to use Hyper-V as a VM host. From the planning perspective, you can still install Windows Server 2008 on this computer and use it as a VM host; it is just that the host platform will be Virtual Server 2005 R2 SP1 rather than Hyper-V.

Alternatively, you could have a similarly powerful computer that has the 64-bit version of Windows Server 2003 R2 installed. Your organization might not be ready to upgrade the operating system of this computer to Windows Server 2008, but you might want to use the computer as a VM host. Because Hyper-V can be deployed only on Windows Server 2008 x64, you will need to include Virtual Server 2005 R2 SP1 in your operating system virtualization plans until you can upgrade the computer operating system to Windows Server 2008 x64.

Although you can use Virtual Server 2005 R2 SP1 as a key component in an operating system virtualization strategy, you must remember the following limitations when planning virtual host deployment:

  • Virtual Server 2005 R2 SP1 cannot host x64 bit VMs—even if the platform that Virtual Server 2005 R2 SP1 is installed on is a 64-bit operating system.

  • Virtual Server 2005 R2 SP1 does not support symmetric multiprocessing (SMP) in the VM environment.

  • Virtual Server 2005 R2 SP1 supports a maximum of four virtual network adapters.

  • Virtual Server 2005 R2 SP1 supports a maximum of 64 concurrent VMs.

More Info: More on Virtual Server 2005

To learn more about Virtual Server 2005, consult the following page on Microsoft’s Web site:


Hyper-V is a Windows Server 2008 feature that allows you to run virtualized computers under x64 versions of Windows Server 2008. Hyper-V is a hypervisor-based technology. A hypervisor is a software layer between the hardware and the operating system that allows multiple operating systems to run on a host computer at the same time. Hyper-V has many similarities to Virtual Server 2005 R2 in terms of functionality, although, unlike Virtual Server 2005 R2, Hyper-V is built directly into the operating system as a role and does not sit above the operating system as an application. Apart from being a feature included with the operating system, Hyper-V has the following differences from Virtual Server 2005 R2 SP1:

  • Hyper-V allows you to run 64-bit VM guests. Hyper-V can concurrently host 32-bit and 64-bit VM guests.

  • Hyper-V supports SMP in the VM environment.

  • Hyper-V can host as many concurrent VMs as the hardware supports.

  • Hyper-V can be configured as a part of a failover cluster, so that a VM fails over across the network to a server running Hyper-V in a recovery site.

  • Hyper-V can be used on a Windows Server 2008 computer installed using the Server Core option. You can manage Hyper-V on a Server Core computer using the WMI interface or a remote session using the Hyper-V manager console.

  • Hyper-V guests can have a maximum of four virtual SCSI controllers per VM.

  • Hyper-V guests can have a maximum of eight virtual network adapters per VM.

  • The Enterprise and Datacenter editions of Windows Server 2008 include licenses to run virtualized instances of the operating system using Hyper-V.

Creating Virtual Machines

Creating a VM on a Hyper-V host is relatively simple and involves running the New Virtual Machine Wizard from the Virtualization Management console. To create the virtual machine, perform the following steps:

Specify a name and location for the VM. Placing a VM on a RAID-5 volume—or, even better, a RAID 0+1 or RAID 1+0 volume—ensures redundancy. You should avoid placing VMs on the same volume as the host operating system. The name of the VM does not need to be simply the computer’s name but can include other information about the VM’s functionality.

Specify memory allocation. The maximum amount of memory depends on the amount of RAM installed on the host computer. Remember that each active VM must be allocated RAM and that the total amount of allocated RAM for all active VMs and the host operating system cannot exceed the amount installed on the host computer.

Specify networking settings. Specify which of the network cards installed on the host will be used by the VM. Where you expect high network throughput, you might add an extra network card and allocate it solely to a hosted VM.

Specify a virtual hard disk. VMs use flat files to store hard disk data. Hyper-V mounts these files, and they appear to the VM as a normal hard disk drive that can even be formatted and partitioned. When creating a virtual hard disk, you should specify enough space for the operating system to grow, but do not allocate all available space if you intend to add other VMs later.

Specify operating system installation settings. In the final stage of setting up a VM, you specify how you will install the operating system: from an image file, such as an .ISO file; from optical media, such as a DVD-ROM; or from a network-based installation server, such as Windows Deployment Services (WDS).

From this point you can turn on the VM and then begin the installation process using the method that you selected in step 5.

Managing Virtualized Servers

You manage Hyper-V through the Hyper-V Manager console, shown in Figure 1. You can use this console to manage virtual networks, edit and inspect disks, take snapshots, revert to snapshots, and delete snapshots, as well as to edit the settings for individual VMs. You can also mount virtual hard disks as volumes on the host server should the need arise.

Figure 1. Virtualization Management console


Snapshots are similar to a point-in-time backup of a virtualized machine. The great benefit of snapshots is that they allow you to roll back to an earlier instance of an operating system far more quickly than any other technology would. For example, assume that your organization hosts its intranet Web server as a VM under Hyper-V. A snapshot of the intranet Web server is taken every day. Because of an unforeseen problem with the custom content management system, the most recent set of updates to the intranet site have wiped the server completely. In the past, as an administrator, you would have to go to your backup tapes and restore the files. With Hyper-V, you can just roll back to the previous snapshot and everything will be in the state it was when the snapshot was taken.


All operating systems that run in a virtualized environment need to be licensed. Products such as Windows Server 2008 Enterprise and Windows Server 2008 Datacenter allow a certain number of virtual instances to be run without incurring extra license costs because the licenses for these editions include the virtualized component. The applications that run on the virtualized servers also need licenses. As with all licensing queries, in more complicated situations you should check with your Microsoft representative if you are unsure whether you are in compliance.

More Info: More on licensing virtual machines

To learn more about what you need to consider when licensing a VM, see

Modifying Hardware Settings

You can edit VM settings. This allows you to add resources like virtual hard disks and more RAM and to configure other settings, such as the Snapshot File Location. Figure 2 shows the Integration Services for a specific VM. Integration Services allow information and data to be directly exchanged between host and VM. To function, these services must be installed on the guest operating system. This task is performed after the guest operating system is set up. You can edit some settings, such as the optical drive settings, while the VM is running. Other settings, such as assigning and removing processors from a VM, require you to turn off the VM.

Figure 2. Modifying the settings of a VM

Not only can you assign processors to VMs, but you can also limit the amount of processor usage by a particular VM. You do this with the Virtual Processor settings shown in Figure 3. This way you can stop one VM that has relatively high processing needs from monopolizing the host server’s hardware. You can also use the Virtual Processor settings to assign a relative weight to a hosted VM. Rather than specifying a percentage of system resources to which the VM is entitled, you can use ratios to weight VM access to system resources. The benefit of using relative weight is that you do not have to recalculate percentages each time you add or remove VMs from a host. You simply add the new host, assign a relative weight, and let Hyper-V work out the specific percentage of system resources that the VM is entitled to.

Figure 3. VM processor allocation

  •  Windows Server 2003 : Troubleshooting Group Policy
  •  Windows Server 2003 : Working with Resultant Set of Policy (part 2)
  •  Windows Server 2003 : Working with Resultant Set of Policy (part 1) - Generating RSoP Queries with the Resultant Set Of Policy Wizard
  •  Configuring Windows 7 NIC Devices (part 2) - Configuring Wireless NIC Devices
  •  Configuring Windows 7 NIC Devices (part 1) - Configuring a Network Adapter & Troubleshooting a Network Adapter
  •  Windows 7 : Configuring Network Connectivity - Understanding Networking
  •  Preparing to Install Windows 7 (part 2) - New Install or Upgrade
  •  Preparing to Install Windows 7 (part 1) - Different Versions of Windows 7 & Hardware Requirements
  •  Maintaining Windows 7 with Backup and Restore (part 2) - Using Advanced Backup Options & Using System Protection
  •  Maintaining Windows 7 with Backup and Restore (part 1) - Creating a Backup & Restoring Files from a Backup
  •  Windows 7 : Configuring Backups and Recovery - Using Advanced Boot Options
  •  Windows Server 2003 : Implementing a GPO (part 2) - Modifying a GPO
  •  Windows Server 2003 : Implementing a GPO (part 1)
  •  Windows 7 : Using Windows Live Calendar (part 3) - Scheduling Appointments and Meetings & Viewing Agendas and Creating To-Do Lists
  •  Windows 7 : Using Windows Live Calendar (part 2) - Sharing Your Calendars with Others & Synchronizing Google Calendar with Windows Live Calendar
  •  Windows 7 : Using Windows Live Calendar (part 1)
  •  Windows 7 : Using Windows Live Contacts
  •  Windows 7: Using Windows Live Mail (part 3)
  •  Windows 7: Using Windows Live Mail (part 2) - Creating, Sending, and Receiving Email
  •  Windows 7: Using Windows Live Mail (part 1) - Setting Up Windows Live Mail and Configuring Email Accounts
    Most View
    ASUS Xonar Phoebus – For Serious Audio Enthusiasts
    Extend Your Android Device’s Battery Life
    Inventory of Broadband Phone Services
    Exchange Server 2010 Administration Overview (part 3) - Using the Graphical Administration Tools, Using the Command-Line Administration Tools
    Samsung 830 Series SSD 256GB - Solid performance and Reliability
    The Modern Office (Part 2)
    Training Get An Extreme Makeover (Part 1)
    Programming Windows Services with Microsoft Visual Basic 2008 : Service Notification
    Open Pandora - Open source gaming handled
    Advice Centre by Photography Experts (Part 4)
    Top 10
    500px - The Stunning Photography Gallery Comes To iPhone
    Cambridge Audio Azur 751R - The Importance Of Being Earnest (Part 2)
    Cambridge Audio Azur 751R - The Importance Of Being Earnest (Part 1)
    Denon AVR 4520 - Stairway To AV Heaven (Part 1)
    Cinebeat - Make The Music Video Fantasy
    iPhoneography - Creating And Editing iPhone Photography As Fine Art
    Nintendo WII U - Mario Upgraded
    Roku Streaming Player LT - Smarten Up Your TV
    Scottevest Transformer Jacket - An Innovative Garment For Gadget Geeks
    Zime (Beta) - Give New Dimensions To Your Calendar Organizational Side