Build Custom Dashboard - Multiple LAWs Across Multiple Azure Subscriptions

Question

Build Custom Dashboard - Multiple LAWs Across Multiple Azure Subscriptions

Taranjeet Malik 611

Hi

We have an environment with multiple Azure subscriptions and multiple Log Analytics Workspaces (LAWs). We want to build custom dashboard that displays Virtual Machine health data, specifically, CPU / Memory / Disk performance and heartbeat for all the VMs across all subscriptions and reporting to different LAW.

Firstly, what's the best way to check whether the VMs are connected to a LAW and which LAW each VM is connected to. The screenshot below shows the some VMs are connected to LAW:

VM LAW

However, if I go the Diagnostics Settings of the VM resource, it only shows this:

Vm diag Settings

Secondly, let's say the VMs are not reporting to Log Analytics Workspace, what's the best (alternate) way(s) to build a custom dashboard to monitor performance and availability for various counters of these VMs across all subscriptions? As the VMs are not reporting to a LAW, we cannot use KQL query to do that - please feel free to correct me.

Thanks

Taranjeet Singh

Suchitra Suregaunkar 4,045 Reputation points Microsoft External Staff Moderator

2025-12-10T12:29:19.41+00:00
Hello Taranjeet Malik

Thank you for posting your query on Microsoft Q&A platform.

You have VMs spread across multiple subscriptions and multiple Log Analytics Workspaces (LAWs), and you want to build a single dashboard that shows VM CPU, Memory, Disk, and Heartbeat data.

To check whether a VM is connected to a Log Analytics Workspace (LAW), and which LAW it is connected is Azure Monitor Agent (AMA) and Data Collection Rules (DCRs).

The AMA controls data flow, and the workspace destination is defined inside the DCR, not in the VM’s diagnostic settings, which is why your diagnostic blade looks empty as Azure Diagnostics Extension is being deprecated.

To verify which LAW a VM is reporting to follow the below steps:

Go to Azure Monitor → Data Collection Rules → Select the DCR → Destinations tab.

This shows the exact LAW(s) the VM is sending logs/perf counters to.

To Cross‑check using Log Analytics (KQL) run the below query inside each workspace:

Heartbeat | summarize by Computer, _ResourceId

If the VM appears here, it is reporting to this workspace.

If VMs are not reporting to a LAW You are correct that without sending data to a LAW, you cannot use KQL to query CPU, Memory, Disk, or Heartbeat, because those tables are created only when a VM sends data via AMA:

Perf

InsightsMetrics

Heartbeat

Without these tables, no unified dashboard can be built.

Below are the Supported alternatives if VMs are not connected to LAW:

Use Azure Monitor Metrics (Platform Metrics): Azure still gives you host‑level metrics even without LAW:

CPU (host level)

Disk IO (host level)

Network metrics

But guest OS metrics such as memory, disk usage, heartbeat are not available.

Reference: https://learn.microsoft.com/en-us/azure/azure-monitor/visualize/tutorial-logs-dashboards

Use VM Insights (Recommended for multi‑subscription dashboards): VM Insights automatically aggregates Guest CPU, Guest Memory, Guest Disk usage, Heartbeat, Dependency maps (optional).

Requirement is AMA + DCR + LAW

Reference: https://learn.microsoft.com/en-us/azure/azure-monitor/vm/vminsights-enable?tabs=portal

Use Azure Workbooks which supports multiple LAWs in one dashboard: You can query multiple workspaces in a single query.

union workspace("<LAW1-ID>").Heartbeat, workspace("<LAW2-ID>").Heartbeat

Reference: https://learn.microsoft.com/en-us/azure/azure-monitor/logs/cross-workspace-query

Since you have Multiple subscriptions, Multiple LAWs, Need cross‑environment VM health reporting the correct and supported solution is:

Use Azure Monitor Agent (AMA) + DCRs + VM Insights + a single Workbook which gives Centralized dashboard, Multi‑LAW queries, Full guest OS metrics, Unified heartbeat, Scalable multi‑subscription design.

If you have any other queries, please do let us know.

Thanks,

Suchitra.

1 answer

Your answer

Answer 1

Taranjeet Malik 611

Hi

Thanks for the detailed response. Can you clarify the following please:

Looking at my requirement, what is the minimum required to achieve it?
1. AMA + DCR + LAW OR
2. AMA + DCRs + VM Insights
Is VM Insights an replacement for LAW here? I've checked and we do have a certain population of VMs that have VM Insights enabled:
The Data Collection Rule (DCR) for Windows has no Objects (CPU, Memory, Disks) selected:

VMInsights

However, the JSON object of the DCR, it shows something called as VMInsightsPerfCounters. Could this be something that may hold data we needed to build the Dashboard? how can I check that?

DCR JSON

I can see that the Table named Perf is available, but it doesn't return anything when queried:

No Results 1

Can see the Schema of the Perf table: Perf Table Schema

Thanks

Taranjeet Singh

Suchitra Suregaunkar 4,045 Reputation points Microsoft External Staff Moderator

2025-12-11T09:29:58.63+00:00
Hello Taranjeet Malik

The minimum required to build a dashboard with CPU / Memory / Disk / Heartbeat across VMs: You must have all three of the following:

Azure Monitor Agent (AMA): It collects guest‑level metrics and replacement for the old Log Analytics Agent (deprecated)

Data Collection Rule (DCR): If defines what performance counters to collect and where to send them (Log Analytics Workspace)

Log Analytics Workspace (LAW): It stores the actual data in tables (Perf, InsightsMetrics, Heartbeat), Workbooks and KQL dashboards read data from here.

VM Insights is not a replacement for LAW, it is a visualization and solution layer that sits on top of AMA + LAW. It does not store data by itself. It still requires AMA + DCR + LAW underneath.

Enabling VM Insights automatically gives CPU/Memory/Disk only if the DCR includes VMInsights performance counters.

Your screenshot shows:

"counterSpecifiers": { "\\VmInsights\\DetailedMetrics" } "name": "VMInsightsPerfCounters"

This means the DCR is configured to collect VM Insights guest performance counters, even though the “CPU / Memory / Disk” checkboxes in the portal UI look empty. So the JSON is correct. The UI does not show VMInsights counters. This is expected behavior.

Your Perf table empty happens in two situations:

A. The VM is not actually reporting AMA metrics to this specific LAW

Check via:

Azure Monitor → Data Collection Rules → Resources

Is the VM listed?

Is “Azure Monitor Logs” configured as a destination?

Reference: https://learn.microsoft.com/en-us/azure/azure-monitor/data-collection/data-collection-rule-structure#destinations

B. VM Insights counters do not populate the Perf table: This is a common misunderstanding. VM Insights sends most guest metrics to InsightsMetrics, not to Perf.

Examples: Memory Utilization, Logical Disk Usage, CPU Utilization, Available Memory, Disk Queue Length.

Run this instead:

InsightsMetrics |

If data appears here → VM Insights is working.

To confirm whether VM Insights Performance Counters are reaching the workspace

Run these KQL queries:

Heartbeat (to verify workspace connection)

Heartbeat | summarize by Computer

VM Insights CPU / Memory / Disk counters:

InsightsMetrics | |

Perf table (only host OS perf counters, not VM Insights):

Perf |

If Perf is empty but Insights Metrics has data→VM Insights is working as expected.

If you have any other queries, please do let us know.

Thanks,

Suchitra.

Share via

Build Custom Dashboard - Multiple LAWs Across Multiple Azure Subscriptions

1 answer

Your answer