High CPU instances detected on the VM nm-0 in the last 24 hours

Question

High CPU instances detected on the VM nm-0 in the last 24 hours

Fredi Nonyelu 40

My VM is not reachable. I restarted and could access for about 1 hour before it became inaccessible again. It says there is Instances of High CPU detected on the VM in last 24 hrs but nothing is running and it is still not reachable.

Anonymous

2025-11-25T17:14:39.93+00:00
Hi Fredi Nonyelu

Thanks for reaching out Q/A. To know more understand about the High CPU and VM unreachable issue. Could you please provide the below details.

When did you first notice the high CPU instances and the VM becoming unreachable?

Have there been any recent changes or updates applied to the VM, such as software installation, configuration changes, or patching?

Are there any specific workloads or processes that normally run on this VM that might cause spikes in CPU usage?

Have you checked the Azure Monitor or diagnostic logs for any alerts or spikes in CPU usage during the affected period?

Did you try performing a full stop (deallocate) and start of the VM, and if so, did that temporarily resolve the issue?

Are there any installed extensions or agents on the VM that might be consuming CPU resources excessively?

Has the VM’s underlying host or hardware experienced any maintenance, failures, or redeployment recently?

Is the VM running a Windows or Linux operating system, and are you able to access the VM via serial console or any other recovery options?

When have you created VM and what VM size you are using?

Could you please share the boot diagnostics screenshot?

Please refer below troubleshooting documentation if CPU is high:

https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/windows/troubleshoot-high-cpu-issues-azure-windows-vm

Additionally, could you please check the private message and provide necessary details.
Fredi Nonyelu 40 Reputation points

2025-11-25T17:22:54.22+00:00
When did you first notice the high CPU instances and the VM becoming unreachable? Today

Have there been any recent changes or updates applied to the VM, such as software installation, configuration changes, or patching? Engineer was updating our code on the VM.

Are there any specific workloads or processes that normally run on this VM that might cause spikes in CPU usage? Yes, our code processing video stream image.

Have you checked the Azure Monitor or diagnostic logs for any alerts or spikes in CPU usage during the affected period? Yes

Did you try performing a full stop (deallocate) and start of the VM, and if so, did that temporarily resolve the issue?

Yes

Are there any installed extensions or agents on the VM that might be consuming CPU resources excessively? Possibly

Has the VM’s underlying host or hardware experienced any maintenance, failures, or redeployment recently? I did a redeployment to try to fix it.

Is the VM running a Windows or Linux operating system, and are you able to access the VM via serial console or any other recovery options? Windows. Unable to access by RDP

When have you created VM and what VM size you are using? 3 years ago - 2GHz CPU 8G RAM

Could you please share the boot diagnostics screenshot? I cannot access the VM
Fredi Nonyelu 40 Reputation points

2025-11-25T17:23:23.8866667+00:00

I managed to create a ticket with the email you sent.

Answer accepted by question author

0 additional answers

Your answer

Anonymous

2025-11-25T17:14:39.93+00:00

Hi Fredi Nonyelu

Thanks for reaching out Q/A. To know more understand about the High CPU and VM unreachable issue. Could you please provide the below details.

When did you first notice the high CPU instances and the VM becoming unreachable?

Have there been any recent changes or updates applied to the VM, such as software installation, configuration changes, or patching?

Are there any specific workloads or processes that normally run on this VM that might cause spikes in CPU usage?

Have you checked the Azure Monitor or diagnostic logs for any alerts or spikes in CPU usage during the affected period?

Did you try performing a full stop (deallocate) and start of the VM, and if so, did that temporarily resolve the issue?

Are there any installed extensions or agents on the VM that might be consuming CPU resources excessively?

Has the VM’s underlying host or hardware experienced any maintenance, failures, or redeployment recently?

Is the VM running a Windows or Linux operating system, and are you able to access the VM via serial console or any other recovery options?

When have you created VM and what VM size you are using?

Could you please share the boot diagnostics screenshot?

Please refer below troubleshooting documentation if CPU is high:

https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/windows/troubleshoot-high-cpu-issues-azure-windows-vm

Additionally, could you please check the private message and provide necessary details.
Fredi Nonyelu 40 Reputation points

2025-11-25T17:22:54.22+00:00

When did you first notice the high CPU instances and the VM becoming unreachable? Today

Have there been any recent changes or updates applied to the VM, such as software installation, configuration changes, or patching? Engineer was updating our code on the VM.

Are there any specific workloads or processes that normally run on this VM that might cause spikes in CPU usage? Yes, our code processing video stream image.

Have you checked the Azure Monitor or diagnostic logs for any alerts or spikes in CPU usage during the affected period? Yes

Did you try performing a full stop (deallocate) and start of the VM, and if so, did that temporarily resolve the issue?

Yes

Are there any installed extensions or agents on the VM that might be consuming CPU resources excessively? Possibly

Has the VM’s underlying host or hardware experienced any maintenance, failures, or redeployment recently? I did a redeployment to try to fix it.

Is the VM running a Windows or Linux operating system, and are you able to access the VM via serial console or any other recovery options? Windows. Unable to access by RDP

When have you created VM and what VM size you are using? 3 years ago - 2GHz CPU 8G RAM

Could you please share the boot diagnostics screenshot? I cannot access the VM
Fredi Nonyelu 40 Reputation points

2025-11-25T17:23:23.8866667+00:00

I managed to create a ticket with the email you sent.

Answer 1

Hi Fredi Nonyelu

Thank you for sharing the details. Based on our analysis we have performed the below checks

We inspected Boot Diagnostics and accessed the Serial Console. Both tools confirmed that the operating system was healthy, and the VM booted correctly without underlying OS corruption or disk-related issues.

Upon review, the VM’s provisioning state was "Updating," and an extension was in a "Failed" state. This platform updating or extension failure can temporarily impact VM accessibility until resolved.

We reviewed Performance Insights and CPU metrics, which showed that CPU utilization was consistently high. This confirms that the current VM size was not sufficient for the workload. Due to this sustained utilization, the VM was under resource pressure, which contributed to the access issue.

After redeployed and restarted the VM, access was restored after ~20 minutes. Resizing from Standard_D2as_v5 → Standard_D4as_v5 (4 vCPU, 16 GiB) helped stabilize performance and cx able to access the RDP.

Reference: https://learn.microsoft.com/en-us/azure/virtual-machines/sizes/resize-vm?tabs=portal

Troubleshoot high-CPU issues on Azure Windows virtual machines

Best Practices Before Resizing

To ensure a smooth and safe resize operation, please follow these steps:

Create a snapshot of the OS disk as a backup: Go to VM → Disks → Select OS Disk → Create snapshot.
Make sure the VM is in a Deallocated state: Stop the VM → Resize → Start the VM again.

Following these steps helps avoid failures during resizing and ensures you have a recovery option in case anything goes wrong.

Reference: https://learn.microsoft.com/en-us/azure/virtual-machines/windows/expand-disks

Anonymous

2025-11-26T12:25:32.1366667+00:00

Hi Fredi Nonyelu

As issue got resolved. Could you please accept the answer and upvote it so it will be helpful to community members. Thank you.