Troubleshooting Common Hyper-V Errors (Part 1)

by [Published on 6 Oct. 2011 / Last Updated on 6 Oct. 2011]

This article examines some of the more common error messages that Hyper-V administrators are likely to receive, as well as the solutions to those errors.

If you would like to read the other parts in this article series please go to:

Introduction

Although Hyper-V generally works pretty well, errors can and sometimes do occur. That being the case, I wanted to write a short article series outlining some of the more common errors that you are likely to encounter in a Hyper-V environment. As I do, I will provide you with the solutions to those errors.

Memory Errors

One especially common error is a memory related error indicating that there is not enough memory in the system to start the virtual machine. You can see with this error looks like in Figure A below:


Figure A: Hyper-V cannot start virtual machines and with sufficient memory is available.

What this error is really saying is that you have allocated more memory to the virtual machine than what is presently available on the system. This isn't to say that the system lacks sufficient physical memory to start the virtual machine (although it may), but rather that there simply isn't enough memory currently available. Most often this error occurs when trying to start a virtual machine on a Hyper-V server when several other virtual machines are already running and have consumed the majority of the server’s memory.

Microsoft Emulated IDE Controller Error

Another especially common error that you are likely to encounter is a condition in which a virtual machine fails to start citing a problem with the Microsoft emulated IDE controller. You can see with this error looks like in Figure B below:


Figure B: Problems with the emulated IDE controller may sometimes prevent virtual machines from starting.

This error occurs when two virtual machines try to use the same DVD drive. To resolve this error, go to the virtual machine’s Media menu and un-capture the DVD drive. If the virtual machine needs access to the DVD drive then you will have to determine which virtual machine is presently using it and release the DVD drive from that virtual machine.

Virtual Machine is Paused – Critical

Occasionally you may encounter a situation in which a virtual machine that was previously working without any issues suddenly pauses itself and displays a status of Paused – Critical. This particular issue occurs when the physical volume that is hosting the virtual hard drive file runs out of disk space.

When you create a Hyper-V virtual machine you are asked how large to make the virtual hard drive file. By default, Windows creates a dynamically expanding virtual hard disk file. This means that the virtual hard disk starts out very small regardless of the size that you specify. As you add data to the virtual hard disk, the virtual hard disk file dynamically expands to accommodate the data. Because of the way that dynamically expanding virtual hard disks work, it is possible to overcommit a Hyper-V server’s storage. Overcommitting storage resources does not initially cause any problems, but as the virtual hard disks grow they may eventually run the server out of physical disk space, resulting in virtual machines being paused and displaying a status of Paused – Critical.

Unsupported Guest OS

When you attempt to install the Hyper-V Integration Services, you may receive an error stating that the guest operating is unsupported. In some cases this error message is legitimate. For example, you won't be able to install the Integration Services on a virtual machine that is running Windows NT or Linux. However, there may be times when you receive an Unsupported Guest OS error message on an operating system that does support the Integration Services.

When this happens, the problem is almost always related to a missing service pack. In some cases, Hyper-V will actually tell you which service pack is required. For example, the figure below illustrates an error message that was displayed on a virtual machine running Windows Server 2003 with Service Pack 1. In this particular case, the error actually tells us that Service Pack 2 is required. In some cases though, you may simply see an error message stating that the guest operating system is not supported without any additional information. When this happens, your best bet is to check the Microsoft website to see what service pack is required in order for the operating system to support the Integration Services.


Figure C: The Hypervisor is not Running

Yet another common Hyper-V error that you may encounter occurs when attempting to start a virtual machine. The error, shown in Figure D below, indicates that the virtual machine could not be started because the hypervisor is not running.


Figure D: This error occurs as the result of an incorrect BIOS setting. In order for the hypervisor to run, hardware virtualization and data execution prevention must both be enabled within the system’s BIOS.

Registry Hive Recovered

One particular error that has practically led to me ripping my hair out has to do with the registry corruption on the guest machine. The error (which seems to occur on guest machines running Windows Server 2003 and Windows Server 2003 R2) indicates that registry hive SOFTWARE was corrupted and that it has been recovered. The error goes on to say that some data may have been lost, as shown in Figure E.


Figure E: Registry corruption problems plague some Hyper-V virtual machines.

So far Microsoft has not yet acknowledged this particular problem, even though it seems to occur on a fairly consistent basis. Don't get me wrong. Not every Hyper-V virtual machine that is running Windows Server 2003 or Windows Server 2003 R2 is prone to this problem. The problem seems to be hardware specific. In my own lab for example, I have two physical servers on which the error occurs on a regular basis, but three other servers that have never once produced this error. The servers that exhibit the problematic behavior are older than the ones that do not. At one point I had hoped that a bios flash might fix the problem, but it did not.

The registry corruption problem seems to occur semi-randomly, but it always coincides with the reboot of a virtual machine. I have experienced the problem with guest operating systems running both the 32-bit and the 64-bit versions of Windows Server 2003 and Windows Server 2003 R2. The problem occurs regardless of whether the host server is running the RTM release of Windows Server 2008 or if it is running Windows Server 2008 R2. My advice for coping with this particular error is to avoid running Windows Server 2003 virtual machines if possible. If you must run Windows Server 2003 or Windows Server 2003 R2 then try to host those virtual machines on your newest physical servers.

Conclusion

In this article, I have discussed several simple errors that you are likely to encounter when working in a Hyper-V environment. In Part two I will conclude the series by discussing several additional errors that you may encounter as you work with Hyper-V. As I do, I will also show you how to get around those errors.

If you would like to read the other parts in this article series please go to:

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