Purpose of Diagnostics Agent and Azure Monitor Agent

1. Diagnostic Extensions requires firewall access and may require to enable private endpoint to fetch the metrics from storage accounts and may encounter issues in retrieving data & managing the associated storage costs.
2. Until Applications Manager v171300 we relied on Diagnostics Extensions (DE), but starting from Applications Manager v171400 we also support Azure Monitor Agent (AMA)  to overcome these limitations.
   
1. Refer to this document to know about the agent supported for different server distributions.

Detailed Steps to enable Azure Monitor Agent in Azure Portal

1. Log in to Azure Portal (https://portal.azure.com).
   
2. Navigate to 'Data collection rules' using search bar and create a new resource under it for agent installation.
3. Create a new Data Collection Rule
   
1. In Basics tab, Select Platform Type as 'Windows' or 'Linux' or 'All' based on the respective virtual machine OS type.
2. In Resources tab, click on 'Add resources' and select the respective Virtual machines.
   
3. In Collect and deliver tab, click on 'Add data source' and select the Data source type as Performance Counters.
   
1. Under Performance Counters, all the listed categories of Basic are chosen by default, and the metrics monitored in Applications Manager are included in it. If the user wants to enable agent only for APM monitored metrics, switch to Custom and select the metrics listed in the below table Windows Metrics Mapper Table or Linux Metrics Mapper Table based on the OS type.
   
   
1. In Destination, click 'Add destination' and Specify destination type as Azure Monitor Metrics (preview). After that, click on 'Add data source'.
   
   
2. Proceed to click on 'Review + create' and review the configurations & click 'Create' to deploy the resource for agent installation.
4. Confirm the status of the installed agent is Provisioning succeeded.
   
1. Navigate to the respective virtual machine and ensure the virtual machine is in Running state. Then select Extensions + applications under 'Settings' in the Left Panel.
   
2. Ensure the status is 'Provisioning succeeded' for AzureMonitorWindowsAgent (or) AzureMonitorLinuxAgent based on OS type of the VM.
   
3. If agent status is not in succeeded state, please check the troubleshooting steps.
   
   
5. Ensure the metrics are added under Azure Monitor Metrics.
   
1. In the respective virtual machine, select Metrics under Monitoring in the Left Panel.
   
2. Click on 'Add metric' and select 'Metric Namespace' as  Virtual Machine Guest for Windows (or) azure.vm.linux.guestmetrics for Linux.
   
3. Verify whether all the Applications Manager supported metrics are listed under 'Metric' list.

Windows Metrics Mapper Table

Linux Metrics Mapper Table

Metric Name in Data Collection Rule	Metric Name in Azure Monitor Metrics	Metric Name in Applications Manager
Processor(*)\% IO Wait Time	cpu/usage_iowait	IO Wait Time (%)
Processor(*)\% Idle Time	cpu/usage_idle	Idle Time (%)
Processor(*)\% Processor Time	cpu/usage_active	Processor Time(Linux) (%)
Memory(*)\% Used Memory	mem/used_percent	Memory Utilization
Memory(*)\Available MBytes Memory	mem/available	Available Memory
Memory(*)\Used Memory MBytes	mem/used	Used Memory
Memory(*)\% Available Memory	mem/available_percent	Available Memory %
Memory(*)\% Used Swap Space	swap/used_percent	Used Swap Memory %

To know about the list of metrics supported for Azure Virtual Monitor under all methods please refer this help document.

Memory Utilization metric in Azure Linux Virtual Machine monitors is supported only for 'Azure monitor agent' agent type from Applications Manager v171900.

Enabling Azure Monitor Agent in Applications Manager

1. Navigate to the respective virtual machine monitor in Applications Manager and click on edit monitor page. Ensure the Agent Type is selected as Azure monitor agent.
   
2. By default Agent Type will be opted as 'Azure monitor agent' and for existing monitors before the v171400 Agent Type will be Diagnostic agent.

For Azure Government Cloud VM monitors, 'Azure monitor agent' agent type is not supported and by default 'Diagnostic agent' will be selected.

Troubleshoot: AM Agent not in Provisioning succeeded state

1. Ensure Python 2 is installed in respective virtual machine. Refer to documentation for Python installation procedures.
   
2. In the respective virtual machine, under Extensions + Applications, if the Status of AzureMonitorWindowsAgent or AzureMonitorLinuxAgent is not 'Provisioning succeeded', click on the agent and review the Status message . Take necessary actions as indicated in the message. Example: Installing required packages to ensure proper configuration. Refer documentation to know the requirements for Agent installation.

Other Relevant Information

1. Diagnostic Extension is now considered a legacy approach and it is limited to some server distributions. It is recommended to switch to Azure Monitor Agent (AMA).
   
2. In Applications Manager to fetch agent metrics for Azure Virtual Machine monitor using 'Diagnostics agent', Contributor role is required. Whereas for 'Azure monitor agent' Reader role is sufficient to fetch data.
3. From Applications Manager v171400,  Azure monitor agent is supported. Refer help documentation to know more.