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Azure Monitor agent not sending custom text logs for arm machines

Charitarth T 0 Reputation points
2025-04-29T13:15:11.3966667+00:00

Even though both the AMD and ARM Azure Virtual Machines are using the same Data Collection Rules (DCR) and Data Collection Endpoints (DCE), I’m seeing that the Azure Monitor Agent (AMA) is only sending custom text logs from the AMD machines. The ARM machines, even though they have the same setup, aren’t sending any logs. I ran into this issue specifically while trying to send custom text logs to a table in the Log Analytics workspace. That said, heartbeats from the ARM machines are still coming through just fine.

If anyone has seen this before or has any ideas on how to fix it, I’d really appreciate your help. Thanks in advance!

Azure Monitor
Azure Monitor
An Azure service that is used to collect, analyze, and act on telemetry data from Azure and on-premises environments.
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  1. Ashok Gandhi Kotnana 6,355 Reputation points Microsoft External Staff
    2025-04-29T14:31:44.9266667+00:00

    Hi @Charitarth T ,

    As confirmed, heartbeat signals from the virtual machines are being received, indicating that the Azure Monitor Agent (AMA) is operational on both AMD and ARM-based VMs.

     However, we suspect that custom text log ingestion into the Log Analytics workspace is not functioning as expected on the ARM-based VMs. To isolate and investigate this issue further, we recommend the following actions:

     Please create a dedicated DCR for the ARM-based VMs. This will help ensure clarity in data flow and avoid any configuration conflicts with existing DCRs used by AMD-based VMs.

     Note: Creating and assigning a DCR does not incur any additional cost.

     1. Log Format

    Ensure that your custom log files follow the correct format:

    Each log entry should begin on a new line.

    If using the timestamp delimiter, the timestamp must be at the beginning of each log entry and follow one of the supported formats below:

     Supported Timestamp Formats:

     YYYY-MM-DD HH:MM:SS M/D/YYYY HH:MM:SS AM/PM Mon DD, YYYY HH:MM:SS yyMMdd HH:mm:ss ddMMyy HH:mm:ss MMM d hh:mm:ss dd/MMM/yyyy:HH:mm:ss zzz yyyy-MM-ddTHH:mm:ssK

      

    If a matching timestamp is not detected, the End of Line (EOL) is used as the default delimiter.

     2. Log File Location

    Confirm that the log files are stored on a local drive of the ARM-based VMs.

    Ensure that the files are not subject to circular logging or overwriting, which could prevent AMA from reliably reading the content. Please refer to the following Microsoft documentation for detailed guidance:

    https://learn.microsoft.com/en-us/azure/azure-monitor/vm/data-collection-log-text https://learn.microsoft.com/en-us/azure/azure-monitor/vm/data-collection-log-text#text-file-requirements-and-best-practices

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