Resize b4 ms,b2ms - d4as_v4,d2as_v4 ,not showing in os level and cpu degradation.

vakati lokesh 20 Reputation points
2026-07-25T05:31:15.65+00:00

we was running into CPU overutilization on my VM's. So I decided to upgrade my VM size from B4ms (4vCPUs and 16GB RAM) to D4as_v4 (4vCPUs | 16GB RAM).

I can see that the upgraded size is reflecting correctly. However, upon logging in the vCPUs are showing as 2vCPUs and not 4vCPUs.

Compared with my other VM's, these machines are running the exact OS and sizing showing the correct vCPU - 4.

My VM shows Standard D4as v4 (4 vcpus, 16 GiB memory) from the Azure Portal but from the OS layer its still running (2vCPUs and 16GB RAM).

I have tried rebooting the machine, re-deploying to a new host and even check via msconfig and the result shows only 2 (number processors) even though still less cpu.

Operating system

Windows (Windows Server 2016 Standard)

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Answer accepted by question author
TP 163.2K Reputation points Volunteer Moderator
2026-07-25T08:30:18.1133333+00:00

Hi,

1. Please confirm that you do not have total number of vCPUs constrained to 2. To check this please navigate to Overview blade of your VM, scroll down under the Properties -- Size and verify it does not show as 2 of 4 (Constrained).

User's image

If it is showing as constrained please navigate to Availability + scale -- Size blade, click on Customize link, increase vCPUs to 4, and then restart your VM to apply the change.

User's image

2. In Device Manager, does it show 4 processors or only 2?

3. What do you have under HKLM\ SYSTEM\ CurrentControlSet\ Control\ Session Manager\ Memory Management\ key? Please post screenshot similar to below.

Specifically, do you have FeatureSettingsOverride and FeatureSettingsOverrideMask ?

enter image description here

Depending on what you have in your registry, the issue may be related to the vulnerability mitigation as described in this article:

KB4072698: Windows Server and Azure Stack HCI guidance to protect against silicon-based microarchitectural and speculative execution side-channel vulnerabilities

Assuming they are present, I believe if you were to remove those two registry values (FeatureSettingsOverride and FeatureSettingsOverrideMask) and restart your server would show 4 logical processors. If you choose to try this, please make sure you have verified backup before making changes just in case you change something and the server refuses to boot. I don't expect this, but it is sound precaution always.

Before making any changes I recommend you read the article, download the SpeculationControl module, run Get-SpeculationControlSettings and examine the output, and then decide what you want to do.

Please click Accept Answer and upvote if the above was helpful.

Thanks.

-TP

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