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Microsoft Virtual Hard Disk FAQ

Find the answers to the most frequently asked questions about VHDs.

General

Q. What is virtual machine technology?
A.Virtual machine technology applies to both server and client hardware. Virtual machine technology enables multiple operating systems to run concurrently on a single machine. In particular, Microsoft Virtual PC products enable one or more operating systems to run on the same computer system as the current Windows operating system. Today, many x86-based operating systems are supported by Virtual PC 2007 and Virtual Server 2005 R2. In addition, Virtual PC for Mac enables one or more other operating systems to run on the Macintosh operating system so that users can run a Windows operating system and Windows applications on a Macintosh. With Windows 2008 and Hyper-V, x64-based operating systems are also supported in a virtualized environment allowing the VM to fully leverage the power of x64 computing.
  
Q.What is virtual machine technology used for?
A.

Virtual machine technology serves a variety of purposes. It enables hardware consolidation, because multiple operating systems can run on one computer. Key applications for virtual machine technology include cross-platform integration as well as the following:

  • Server consolidation. If several servers run applications that consume only a fraction of the available resources, virtual machine technology can be used to enable them to run side by side on a single server, even if they require different versions of the operating system or middleware.
  • Consolidation for development and testing environments. Each virtual machine acts as a separate environment, which reduces risk and enables developers to quickly recreate different operating system configurations or compare versions of applications designed for different operating systems. In addition, a developer can test early development versions of an application in a virtual machine without fear of destabilizing the system for other users.
  • Legacy application re-hosting. Legacy operating systems and applications can run on new hardware along with more recent operating systems and applications.
  • Software demonstrations. With virtual machine technology, users can quickly recreate a clean operating system environment or system configuration.
  • Simplify disaster and recovery. Virtual machine technology can be used as part of a disaster and recovery plan that requires application portability and flexibility across hardware platforms.
  
Q.Is there a cost to use VHDs for evaluations?
A.No. The VHDs are available as a free download from www.microsoft.com/vhd.
  
Q.How long is the evaluation period for the VHD?
A.Open evaluations for customers will enable a 30-day evaluation time period for a VHD running on Windows Server 2003 and a 60-day evaluation time period for a VHD running on Windows Server 2008.
  
Q.How does this differ from Virtual Labs?
A.Virtual Labs is a testing environment for products and scenarios over the internet. The VHD Test Drive Program allows you to run the VHD on your local system using Virtual Server 2005 R2 or Hyper-V.
  
Q.What other software/appliances will be available via the new VHD Test Drive program?
A.You can find the current list of available VHDs from the VHD Download Center. Partners and customers can expect to see additional Microsoft software and partner software added to this program. Please check back on this page often to get the latest set of images and also find new images added to the catalog.
  
Q.Will localized versions of the VHDs be made available?
A.The VHDs are currently only available in English.
  
Q.Can I take a VHD available from the VHD catalog and use it in production in my organization?
A.No, The VHDs are intended to be used only for evaluation and test purposes.
  
Q.Can I activate the VHD?
A.No, you cannot activate the VHD. VHD images are created for test and evaluation purposes only. Do not put this image in a production environment.
  

Virtual Server Technical FAQ

Q. What are the requirements for evaluating the software in VHDs?
A.

The system requirements vary based on the VHD downloaded. Please refer to the system requirements mentioned for the specific VHD you have downloaded. The general requirements for using the VHDs are:

  • A system with supported Operating Systems: Windows Server 2003 or Windows XP or Windows Vista
  • Other Requirements: Personal Computer with 1.5 GHz or higher processor and at least 1 GB RAM.
  • Free hard drive space as required by the VHD
  • Super VGA (1024x768) video adapter/monitor
  • Microsoft Virtual Server 2005 R2 software
  
Q.What are the host requirements for Virtual Server?
A.See the System Requirements page or search for “system requirements” in the Virtual Server Administrator’s Guide.
  
Q.How many virtual machines can run per processor?
A.

The number of virtual machines running per host depends on several things, including physical memory, processor, and workload running in the guest. With Virtual Server 2005 R2, you define the amount of memory available to a virtual machine, and that memory allocation can be altered to reflect the needs of the virtual machine.

For more information, see the Virtual Server 2005 R2 Technical Overview White Paper.

  
Q.How much memory do I need to run the virtual machines?
A.You will need sufficient RAM in the physical machine to cover the system requirements for Virtual Server 2005 R2 (see the System Requirements page for more information) plus the amount of RAM allocated to the virtual machine. The virtual machine RAM allocation may be viewed by looking at the configuration page of the virtual machine once it is registered in the Virtual Server 2005 R2 management console.
  
Q.How can I get support for the VHD from the VHD Test Drive catalog?
A.Product support for evaluation purpose can be found through various newsgroups for the different products. The Virtual Server Community page provides a list of newsgroups and communities that can help answer your support needs.
  

Hyper-V Technical FAQ

Q. What are the requirements for evaluating the software in VHDs?
A.

The system requirements vary based on the VHD downloaded. Please refer to the system requirements mentioned for the specific VHD you have downloaded. The general requirements for using the VHDs are:

  • A system with Supported Operating System: Windows 2008 with the Hyper-V role installed
  • Other Requirements: Host computer with 1.5 GHz or higher processor and at least 1 GB RAM.
  • Free hard drive space as required by the VHD
  
Q.What are the host requirements for Hyper-V?
A.See the Technical Information section on http://www.microsoft.com/windowsserver2008/en/us/hyperv-faq.aspx.
  
Q.How many virtual machines can run per processor?
A.The number of virtual machines running per host depends on several things, including physical memory, processor, and workload running in the guest. With Hyper-V, you define the amount of memory and number of processors available to the virtual machine. These resources will be allocated to the virtual machine when it is running.
  
Q.How much memory do I need to run the virtual machines?
A.You will need to sufficient RAM in the physical machine to cover the system requirements for the host operating system plus the amount of RAM allocated to the virtual machine. The virtual machine RAM allocation may be viewed by looking at the settings window of the virtual machine once it is registered in the Hyper-V Manager.
  
Q.How can I get support for the VHD from the VHD Test Drive catalog?
A.Product support for evaluation purpose can be found through various newgroups for the different products. The Virtualization with Hyper-V Community page provides a list of newsgroups and communities that can help answer your support needs.
  

Additional Resources

Q. What is the VHD Image Format Specification license program?
A.Microsoft offers the Virtual Hard Disk (VHD) Image Format Specification freely under the terms of the Open Specification Promise to make it easier for partners to develop VHD-based solutions and continue to enhance the capabilities and extensibility of the VHD format. Full access to the detail specification is available for download from here.
  
Q.Are there any performance tips for Virtual Server 2005 R2 or Hyper-V?
A.Yes. For Virtual Server 2005 R2 please read Virtual Server 2005 Performance Tips for more information. For Hyper-V please read Optimizing Performance on Hyper-V for more information.
  
Q.Are there public newsgroups for Virtual PC, Virtual Server or Hyper-V?
A.
  
Q.Are there Virtualization webcasts available?
A.Yes, numerous webcasts are available.
  
Q.Is there any Virtual Server 2005 R2 capacity planning guidance?
A.Yes. Please read Solution Accelerator for Consolidating and Migrating LOB Applications for guidance on consolidating and migrating LOB applications to Microsoft Windows Server 2003-based solutions, including onto Virtual Server 2005-based virtual machines. It provides technical information and recommendations, processes, build notes, job aids, test scripts, and capacity planning guidance.
  

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