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I am running VMs on 2008 R2 and just tried to add memory to one. So I turned the machine off, increased the memory (static) and turned started it. The "Assigned Memory says "40970 MB" but Windows Task Manager at the VM says "32768" in the total row for physical memory.

Has anyone experienced this before, and can help me explain why this is happening and how to address it?

user3043028
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2 Answers2

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Sounds like this could be a limitation of your guest OS. Please verify that your guest OS supports more than 32GB. 32 is the max for Server 2008 R2 Standard Edition.

Jon Tirjan
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  • Ahhh. It's so obvious now. That's exactly the problem. Didn't think the limit would be so low. Can't believe the jump to the next version up is 4TB. Thank you. – user3043028 Mar 23 '15 at 15:35
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According to this article, Hyper-V assigns a memory buffer, which you can edit under the "Memory Management" page, as described in "Step 3.

The reason why there's more "Assigned Memory" is because Hyper-v allocated more ram to the VM than it's actively using, because the dynamic memory feature is enabled.

The dynamic memory feature lets VMs consume memory dynamically based on the current workload. If an application on a VM is designed to use a fixed amount of memory, it’s better to give that VM exactly the amount of memory it needs instead of using dynamic memory in order to make full use the installed memory.

ilian
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  • I'm using the static option though and still seeing what would be a 20% buffer. The buffer is set to 20% by default, but again, that shouldn't matter if I'm using static right? – user3043028 Mar 22 '15 at 13:15
  • @user3043028 If the memory management option is set to static, the 20% buffer setting should be grayed out and is thus not in effect. If you view the virtual machine in the Hyper-V manager, did you make sure the dynamic memory option is disabled, and the "Memory Demand" property is blank? If not, you should reboot your vm to make sure the changes are in effect. – ilian Mar 22 '15 at 13:33
  • There is a memory buffer of 20% that's showing (if that's what you mean by "Memory Demand"), but I have confirmed it's also set to static memory. This might be a glitch that'll be solved on reboot, but I'll have to wait until tonight to find out. Just doesn't seem to be working as it was designed. – user3043028 Mar 22 '15 at 14:26
  • @user3043028 The "Memory Demand" property can be [seen](http://blogs.technet.com/cfs-file.ashx/__key/communityserver-blogs-components-weblogfiles/00-00-00-54-27-metablogapi/8168.clip_5F00_image0027_5F00_thumb_5F00_68D1E8BA.jpg) when you select your VM in the Hyper-V Management Console. If dynamic memory is turned off, the field should be blank. – ilian Mar 22 '15 at 14:30
  • Dynamic memory is turned off. Thanks for the suggestions though. – user3043028 Mar 22 '15 at 22:48