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David Fraser
Asked: 2010-11-18 01:06:04 +0800 CST

How to get Windows Server 2008 VM to use multiple cores

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I have a Windows Server 2008 machine running in VirtualBox. On initial installation, only one processor was made available, but now I want to run it as a multiprocessor machine.

I have made all four cores available in the VirtualBox settings (as well as enabling VT-x/AMD-V and Nested Paging), but Task Manager still only shows one CPU. However, the four CPU cores are visible in Device Manager under Processors.

In the event log on startup, I can see the following relevant events:

EventLog.6009 Microsoft (R) Windows (R) 6.00.6002 Service Pack 2 Multiprocessor Free
Kernel-Processor-Power.4 Processor 0 exposes the following: 1 idle state(s), 0 performance state(s), 0 throttle state(s)
Kernel-Processor-Power.4 Processor 255 exposes the following: 0 idle state(s), 0 performance state(s), 0 throttle state(s)
Kernel-Processor-Power.4 Processor 255 exposes the following: 0 idle state(s), 0 performance state(s), 0 throttle state(s)
Kernel-Processor-Power.4 Processor 255 exposes the following: 0 idle state(s), 0 performance state(s), 0 throttle state(s)

How can I make this system actually boot up as a multiprocessor machine?

windows-server-2008 virtualbox multi-core

3 Answers

  1. This is a common issue in the worl of PtoV, VtoP etc, but I always forget the resolutions that have worked for me.

    One that springs to mind is deleting the ACPI device from Device Manager

    But here is something thats looks similar to your issue, given that your event log shows all cpus.

    http://www.storagecraft.com/support/forum/only-1-processor-showing-task-manager

    Browse to c:\windows\system32
Right click on HAL.DLL
Click the version tab
Click Internal Name.  Here it will tell you definitly which HAL you are running.

    You want halmacpi, not halaacpi

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  2. It could be that your processor does not support VT-x , if so then 1 core will only be possible.

    Have a look at this thread to get the gist https://superuser.com/questions/33723/getting-2-processors-to-work-with-virtualbox-on-dual-core-celeron

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  3. Ok David, just re-read your Question and I think the problem may lie in the fact that I dont think you can add extra cores to the OS post install (unlike memory). I've never had to do this but it makes sense. To test, why dont you try and install a quick Win OS with the correct settings and see at the end that they have/ havent been picked up...

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