System requirements for Virtual Server

System requirements

Planning a successful deployment of Microsoft® Virtual Server 2005 includes evaluating your requirements for the operating systems and applications that you need to run. You can then use that information to plan the configuration of the physical computer on which you will install Virtual Server.

The minimum requirements that your system should meet will vary depending on the number and type of guest operating systems, the applications you plan to install on the virtual machines, and the anticipated workload. For example, to run multiple virtual machines simultaneously, the physical computer must have at least enough memory to cover the requirements of the host operating system and each guest operating system. You should refer to the system requirements to ensure that your system resources will support your deployment.

Changes have been made to the product that affect this information. For updated information, see the Virtual Server 2005 Release Notes.

Physical computer and host operating system requirements

Following are the minimum system requirements for the physical computer and the host operating system:

  • An x86-based computer with a 550 megahertz (MHz) or faster (1 gigahertz [GHz] recommended) processor with L2 cache, such as processors from any of the following families:
    • Intel—Xeon or Pentium families
    • AMD—AMD64 or Athlon families
    You can run Virtual Server on servers with multiple processors. Virtual Server 2005, Standard Edition can run on servers with a maximum of four processors. Virtual Server 2005, Enterprise Edition can run on servers with more than four processors. The maximum number of processors for Virtual Server 2005, Enterprise Edition is determined by the host operating system.
  • CD-ROM or DVD drive
  • Super VGA (800 x 600) or higher resolution monitor recommended
  • Host operating system:
    The 32-bit version of any of the following operating systems:
    • Microsoft Windows Server™ 2003, Standard Edition
    • Microsoft Windows Server 2003, Enterprise Edition
    • Microsoft Windows Server 2003, Datacenter Edition
    • Microsoft Windows® Small Business Server 2003
    • Microsoft Windows XP Professional
    You should use Microsoft Windows XP Professional as a host operating system only in a non-production environment.
  • For disk space and memory requirements, refer to the following table to determine the minimum required by the host operating system. These requirements are general guidelines only. You should consult the product documentation provided with each operating system for specific requirements.


Host operating system Minimum RAM Minimum disk space

Windows Small Business Server 2003, Standard Edition

256 MB

4 GB

Windows Small Business Server 2003, Premium Edition

512 MB

4 GB

Windows Server 2003, Standard Edition

256 MB

2 GB

Windows Server 2003, Enterprise Edition

256 MB

2 GB

Windows Server 2003, Datacenter Edition

512 MB

2 GB

The World Wide Web Service component of Internet Information Services (IIS) is required on the computer running the Administration Website.
The maximum amount of RAM on the physical machine that is supported by Virtual Server is the maximum amount supported by the host operating system. Each virtual machine runs as a single processor computer regardless of how many processers are on the physical computer. You can configure more virtual machines than there are host processors. You must use the NTFS file system on your host operating system. The Virtual Server security architecture is dependent on the file system security features provided only by NTFS.

The disk space in the previous table is only a starting point in determining how much disk space you will need. It is essential that you allow for the additional space that will be required by all guest operating systems that you plan to deploy. Not only do you need enough disk space for the host operating system and each guest operating system, you must also take into account the extra space needed for each virtual machine's paging file, all dynamically expanding virtual hard disks, and the space needed to save the contents of each virtual machine's RAM when putting the virtual machine into a saved state. For more information, see Best practices for Virtual Server.

Just as in a physical computer, adding memory to a virtual machine will improve performance.

Guest operating system requirements

Virtual Server supports the following guest operating systems:

  • Any 32-bit version of the Microsoft Windows Server 2003 operating systems, except Datacenter Edition
  • Microsoft Windows NT® Server 4.0 with Service Pack 6a (SP6a)
  • Any Microsoft Windows 2000 Server operating system, except Datacenter Edition

You should refer to the product documentation included with each operating system to determine the minimum system requirements for the guest operating system. Be aware that the minimum required disk space you need is the sum of the required disk space of each guest operating system and the host operating system, in addition to disk space for any applications to be installed on the operating systems.

If you plan to run more than one guest operating system simultaneously, you need to add the RAM requirements for all of those operating systems in addition to the RAM required by the host operating system. Additionally, Virtual Server can require up to an additional 32 MB of RAM per virtual machine. To enhance performance, consider increasing the amount of memory beyond the minimum requirements described here and in the product documentation. Note that memory allocated to virtual machines is not available for paging by the host operating system.

Virtual Server can support up to a maximum of 64 virtual machines. The practical limit of how many virtual machines you can run simultaneously depends on system resources, the amount of memory assigned to each virtual machine, and the total memory available on the physical computer. Virtual Server supports up to 3.6 gigabytes (GB) of RAM per virtual machine.

Usage considerations

It is possible to run almost any x86-based application on a virtual machine; however, some applications are not as well suited as others for use on a virtual machine. Although you can run Virtual Server on a multiprocessor computer, each virtual machine can use a maximum of one processor. This means that enterprise-class applications designed to use multiprocessor hardware may not provide adequate performance if you run them on a virtual machine. When deciding whether to run an application on a virtual machine, consider the virtual machine's physical counterpart. In other words, would you run this application on a physical computer that has one processor?

The appropriateness of running an enterprise-class application on a virtual machine depends on anticipated workload and how you intend to use the application. For example, applications such as Microsoft SQL Server™ or Microsoft Exchange Server will run on a virtual machine. However, depending on workload, performance may not meet acceptable levels for your organization. If you need to run such an application for testing or training purposes, the data access demands that affect performance would be very different than if you use the application in a production environment.

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