Virtual Machine Monitoring KQL yielding empty results

Question

I have enabled Azure Monitoring in one of our virtual machine. Is been 4 days the virtual machine is on, below is the query:

Perf
| where ObjectName == "Memory" and
(CounterName == "Available MBytes Memory" or // the name used in Linux records
CounterName == "Available MBytes") // the name used in Windows records
| summarize avg(CounterValue) by bin(TimeGenerated, 15min), Computer, _ResourceId // bin is used to set the time grain to 15 minutes
| render timechart
The output of Perf itself is empty. The same thing goes for Update, it show me zero results.

These are the two extensions I have installed on the VM

Virtual Machine Monitoring KQL yielding empty results

Any Suggestion?

Answer 1

I think you need to setup some data collection rules. The agent extension does not have any default collection beyond the heartbeat table. https://learn.microsoft.com/en-us/azure/azure-monitor/essentials/data-collection-rule-overview

Answer 2

If you have enabled VM Insights, you need to use another Table - InsightsMetrics

InsightsMetrics  
| where Origin == "vm.azm.ms"  
| where Namespace == "Memory" and Name == "AvailableMB"  
| extend TotalMemory = toreal(todynamic(Tags)["vm.azm.ms/memorySizeMB"]) | extend AvailableMemoryPercentage = (toreal(Val) / TotalMemory) * 100.0  
| summarize AggregatedValue = avg(AvailableMemoryPercentage) by bin(TimeGenerated, 15m), Computer, _ResourceId  
| render timechart