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Changes deployed starting on October 24th, 2020 for Azure Monitor for Virtual Machines resulted in sending values of 0 for the network metrics (Network ReadBytesPerSecond, Network WriteBytesPerSecond) to the InsightsMetrics table in Logs. The correct data is not rendered on the Bytes Sent Rate and Bytes Received Rate charts under the Performance tab. The issue only affects Windows VMs that have VM Insights enabled. Linux VMs with VM Insights work as expected.
 
Root cause: The VM Insights Windows Management Pack version 8.0.1.781 has a bug which results in sending 0 for the network metrics to the InsightsMetrics table.
  
Incident Timeline: October 24, 2020, to present

Until we resolve this issue, you can monitor the network metrics by running a log query on the VMConnection table for Bytes sent and received trends. Please refer to the example log query here (https://docs.microsoft.com/azure/azure-monitor/insights/vminsights-log-search#bytes-sent-and-received-trends)
 
We are working hard to roll out a fix as soon as possible. We understand that customers rely on Azure Monitor VM Insights as a critical service and apologize for any impact this incident caused.

– Jack

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