Finding Azure VM and Disk throughput performance.

Paul Shay 21

I have this alert on the Azure disk blade on some of our VM's:

"The configuration of this virtual machine and its attached disk(s) does not allow for the disk(s) to utilize their full throughput performance. The current virtual machine size supports 96 MBps. The total for disk(s) attached to virtual machine 'VM*****' is 250 MBps. You can change the virtual machine size to support additional disk(s) throughput"

Is there a way to get a complete list of our VM's with this problem without clicking through the portal manually checking hundreds of our VM's?

I am thinking along the lines of a powershell script to extract the max throughput of a VM sku and comparing it with the max disk throughputs combined. This is proving harder than it sounds. Does your popup info-box use an api call I can use?

Mounika Reddy Anumandla 830 Reputation points Microsoft Vendor

2024-11-18T04:10:30.8833333+00:00

Hi Paul Shay,
Just checking to see where you stand with the issue.

If you have any further queries, do let us know.

Thank you!

1 answer

Mounika Reddy Anumandla 830 Reputation points Microsoft Vendor

2024-11-12T02:57:07.6133333+00:00

Hi Paul Shay,

Welcome to the Microsoft Q&A Platform!
Good day! I'll be happy to assist you today.

This warning indicates that your current virtual machine (VM) configuration does not allow the attached disks to achieve their full throughput processing capacity. In this case, the VM supports a maximum throughput of 96 MBps, but the connected disks are configured to require a total of 250 MBps.

• Increase VM Size: Select a VM size that supports the required throughput. In your case you need a large VM that supports at least 250 MBps throughput for the attached disk. To help clarify disk performance and how it works when you combine Azure Virtual Machines and Azure disks please go through the below Microsoft documentation.

https://learn.microsoft.com/en-us/azure/virtual-machines/disks-performance

I request you to go through a relevant document which might suit your scenario: https://stackoverflow.com/questions/64667758/get-azure-vm-size-limits-like-throughput-and-iops

Azure offers metrics in the Azure portal that provide insight on how your virtual machines (VM) and disks perform. The metrics can also be retrieved through an API call. Please go through the below documentation: https://learn.microsoft.com/en-us/azure/virtual-machines/disks-metrics.

Hope this helps.
In case I misunderstood the scenario or if you have any further queries, please add more details/context to help me better understand.

If the answer is helpful, please click "Accept Answer" and "Upvote it."
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Paul Shay 21 Reputation points

2024-11-12T16:12:07.6933333+00:00

Hi,

thank you very much for your reply.

Hold on to your hats but believe it or not I've read all those documents and even the stackoverflow answers before posting this.

What I am trying to avoid is doing complicated mathematics and metric analysis on each of our many hundreds of vm's when it seems clear from the notification that MS has access to both disk and VM Throughput maximums already. As you kindly reread to me the original advisory contains "the VM supports a maximum throughput of 96 MBps, but the connected disks are configured to require a total of 250 MBps." So where are they getting 96 MBps and 250 MBps from?

Powershell can not access those fields so is there a way end users can do it via an api call or not?

Best.

Mounika Reddy Anumandla 830 Reputation points Microsoft Vendor

2024-11-13T04:10:13.5466667+00:00

Hi Paul Shay,

We have noticed that you have rated an answer as not helpful. We appreciate your feedback and are committed to improving your experience with the Q&A.
Can you please share the vm sku and the disk details.
Is the disk that you are referring was part of the image that got deployed along with the vm or is it a seperate data disk that you have attached while deploying the vm.
I will try to reproduce in my lab to see if I can get the details through existing rest api's and will update you back.

Thank you!

Mounika Reddy Anumandla 830 Reputation points Microsoft Vendor

2024-11-14T02:28:21.4366667+00:00

Hi Paul Shay,
I have investigated further to gather additional information.
You can use the API call to list all VMs in your subscription, Retrieve VM Size Information, Get Disk Information. The responses from these API calls will be in JSON format. But they are not directly giving the max throughput details. You have to write a customized script to calculate the overall throughput.
https://learn.microsoft.com/en-us/rest/api/compute/virtual-machines/list-available-sizes?view=rest-compute-2024-07-01&tabs=HTTP
https://learn.microsoft.com/en-us/rest/api/compute/disks/get?view=rest-compute-2024-07-01&tabs=HTTP#disksku

I agree that this scenario looks complex than it sounds and needs deeper investigation. If you have a support plan could you please file a support ticket for deeper investigation and do share the answer with us? In case if you don't have a support plan please let us know here. We will be able to help you with a one time free support ticket.Thank You!

Paul Shay 21 Reputation points

2024-11-14T10:35:38.5966667+00:00

Thank you for looking into this Mounika, we do indeed have Unified Enterprise support so I may raise a low priority ticket to see if we can delve into this.
You have anticipated that I've written a custom powershell script to address this.

The script estimates the total disk throughput of Azure VMs based on their attached disks and compares it to the maximum disk throughput allowed for the VM size. It performs the following steps:

Connects to the Azure account.

Sets the Azure subscription context.

Defines a mapping of VM sizes to their maximum disk throughput values.

Retrieves all VMs in the subscription.

For each VM, it:

Gets the VM size and its maximum disk throughput.

Retrieves the disks attached to the VM.

Estimates the total disk throughput based on the disk types.

Compares the total disk throughput to the maximum allowed throughput.

Stores the results, including a status indicating whether the throughput exceeds the maximum allowed.

Exports the results to a CSV file named "VM_Disk_Throughput_Report.csv".

However, there are a lot of variables such as disk caching, vm setup (bursting for instance), networking etc. that make this approach very much an estimate.
This might do for our FinOps guys to make a resizing recommendation to service owners. If I pursue the matter further I'll share the experience here with you.

Best.
P.

Mounika Reddy Anumandla 830 Reputation points Microsoft Vendor

2024-11-15T05:46:25.87+00:00

Hi Paul Shay,
Thank you for reaching back and providing a detailed account of the steps you've taken.

Thank you!
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