Azure Local Memory Utilization

Question

Azure Local Memory Utilization

Handian Sudianto 6,886

Can someone help me to understand Memory Utilization in Azure Local?

We can see from below picture the memory utilization from the host is 91% User's image

But if we see from each VM under this node, the total memory assigned is areound 298GB. Then why from host level the utilization is 91%?

Total physical memory is 512GB, 91% mean 467GB used.

User's image

0 comments

2 answers

Your answer

Answer 1

Jilakara Hemalatha 11,600 Microsoft External Staff Moderator

Hello Handian Sudianto,

Regarding the memory utilization observed on the node: the host-level memory usage includes not only the memory assigned to virtual machines but also memory used for platform operations such as Storage Spaces Direct (S2D) caching, filesystem cache, and networking buffers. This is expected behavior and helps optimize overall performance of the node and hosted workloads.

For monitoring and verification, you can check the currently available memory using:

Get-Counter '\Memory\Available MBytes' – to view free memory on the host
Get-ClusterPerformanceHistory – to review historical memory usage trends on the cluster

Even if VM-assigned memory totals less than physical memory, the host may still report higher utilization due to these overheads, which is normal in Azure Local environments."

Hope this helps! Please let me know if you have any queries in comment.

Handian Sudianto 6,886 Reputation points

2026-04-07T00:46:02.03+00:00

Hi,

So example to total assigment memory is 25GB then how many physical memory should we have to keep the utilization nor more than 80% for example?

How we can extacly know how much memory for overhead, S2D and other local resources?
Jilakara Hemalatha 11,600 Reputation points Microsoft External Staff Moderator

2026-04-08T05:50:10.0033333+00:00

For capacity planning, there isn’t a fixed overhead value because Azure Local dynamically uses memory for Storage Spaces Direct caching, filesystem cache, and other platform operations.

As a general guideline, you can consider ~20–30% of total memory for host overhead.

For example, if VM allocation is 25 GB and you want to keep utilization under 80%, you may require approximately 40–45 GB of physical memory to accommodate both workloads and platform usage safely.

To better understand actual memory pressure, we recommend checking available memory using: Get-Counter '\Memory\Available MBytes'

This provides a more accurate view than percentage utilization, as much of the used memory is cache and can be reclaimed when needed.

Please refer: https://github.com/MicrosoftDocs/azure-stack-docs/blob/main/azure-local/concepts/monitoring-overview.md
Jilakara Hemalatha 11,600 Reputation points Microsoft External Staff Moderator

2026-04-09T06:01:13.4666667+00:00

Hello Handian Sudianto

Could you please confirm above provided information was resolved your query. Please let me know if you have any queries in comments.
Handian Sudianto 6,886 Reputation points

2026-04-09T07:44:24.9933333+00:00

Hi

For example, if VM allocation is 25 GB and you want to keep utilization under 80%, you may require approximately 40–45 GB of physical memory to accommodate both workloads and platform usage safely.

If you see in my picture above, total memory assigned for all VM is 165.83GB and the utilization is 91%.

I have 512GB physical memory then total memory consumed is 91% x 512GB = 465GB, then because total memory for all VMs is 165.8GB then the host consume 300GB? 300GB is more than 50% and it's true the host consumend very high memory?

Answer 2

On Azure Local, host memory utilization includes more than just the sum of “Assigned memory” for the VMs on that node.

From the Azure Local metrics model:

At node (host) level, Cluster node Memory Used and Percentage Memory represent all memory that is not available on the node:
- memory allocated to guest VMs (Percentage Memory Guest),
- memory used by the host OS and infrastructure services (Percentage Memory Host),
- any cache or other reserved memory.
At VM level, VM Memory Assigned is only the memory assigned to that VM, and VM Memory Used / VM Memory Available describe usage within that assigned amount.

Therefore, the 91% host utilization (≈467 GB of 512 GB) is:

Host memory used ≈ Guest‑allocated memory (sum of VM Memory Assigned) + Host/infrastructure memory + cache/overhead

The ~298 GB that is visible as “Assigned memory” for the VMs explains only the guest portion. The remaining ~169 GB is consumed by:

Host OS and its processes.
Azure Local infrastructure components and storage stack.
File system and CSV cache.

This is expected behavior: host‑level memory metrics are not just a sum of VM assignments but reflect total node consumption.

To validate this on the cluster:

In Azure portal → Azure Local resource → Metrics, look at:
- Cluster node Memory Total
- Cluster node Memory Used
- Percentage Memory, Percentage Memory Guest, and Percentage Memory Host
Compare Percentage Memory Guest (VM demand) with Percentage Memory (total) to see how much is used by the host and infrastructure.

References:

Monitor Azure Local with Azure Monitor Metrics

Share via

Azure Local Memory Utilization

2 answers

Your answer