Booting Windows 8 from VHD

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My first blog post on TechRepublic, “How to install Windows Server 2008 R2 with Hyper-V and Windows 7 on the same partition” focussed on booting Windows 7 or Windows Server 2008 from a VHD. I used the same concept to deploy Windows 8 to a series of new laptops for my team and we had some interesting findings:

1 – It’s Easy

We were able to use the same methodology to deploy Windows 8 to a VHD as we used for Windows 7 and Windows Server 2008 R2. A brief overview of the process:

1. Create a VDisk

2. Attach it

3. Partition it

4. Format it

5. Install OS

2 – It’s Fast

We weren’t able to detect any performance issues when we used fixed size VHDs. Although we didn’t try it, there is also support for the VHDX format which has a size increase to 16TB (VHDs are limited to 2TB) and can be significantly faster for some workloads depending on block and sector size requirements. Using Dynamic sized VHDs is not recommended.

3 – It’s Portable

We easily moved the VHDs between machines and had no issues. In some cases we had to make some minor changes with BCDEDIT. It’s not as portable as Windows to Go but it is portable and makes for an easy provisioning experience.


4 – It’s Virtual

Although we haven’t finished our testing yet, we fully expect to be able to use the VHD as a virtual machine in Hyper-V. More details in a future post.

5 – It’s Limiting

There are a few things that you can’t do when booting Windows 8 from VHD. The two that we found most readily are:

· The hibernate functionality of a laptop is not available


· The Windows Experience cannot be measured


If there are other issues that you notice, please let me know. I’m now working with Hyper-V 3 in Windows 8 Enterprise and will let you know my finings in a future post.

Picked up by TechRepublic

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It has been a while since I’ve posted anything here but I have a very good reason.  My blog has been picked up by TechRepublic and most of my posts are going to be hosted there for the foreseeable future.   Believe it or not, they actually pay me for this stuff.

I’m going to look into adding the links to my blogroll here but please follow me on TechRepublic if you can.

Here are links to my first four posts on TechRepublic:

  1. How to install Windows Server 2008 R2 with Hyper-V and Windows 7 on the same partition
  2. Costs and risks to consider when planning a move to the public cloud
  3. Don’t overlook these seven problem areas of virtualization
  4. How to optimize VM memory and processor performance


Monitoring Virtual Environments

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We keep hearing that it doesn’t matter if your machine is physical or virtual.  Your software will still work just fine.  That’s true most of the time but there are some exceptions.  Monitoring is one of those exceptions.  In truth, the monitoring tool will work and will give you accurate information but it will be meaningless.

Remember that in a hypervisor based virtual environment, the guest OS is typically unaware that the hardware has been abstracted and that resource scheduling is taking place to provide shared computing resources based on some preset business rules (some guests may be configured to get more resources than others).

In a scenario like this, a legacy monitoring tool that is targeted at the guest VM, may get false positives concerning resource availability.  Typically you might see near 100% CPU consumed.  This will be based on the telemetry coming back from the guest VM indicating that it is nearly out of resources, when in reality, there may be more resources available just not committed or allocated to that VM at that point in time.

To get a more realistic and complete view of what is actually happening, the monitoring tool would need to monitor the hypervisor and all of the guests correlating the telemetry form all of them and providing a more holistic view of the availability of resources.

Products like this are starting to emerge.  Make sure that when you plan to migrate a server or application to a virtual environment you also plan for the monitoring requirements.