Linux VM not available

Question

Hello Support,

Please help troubleshoot the VM (Linux) issue - lost the availabiltiy out of the blue, and within 10 minutes, the VM is available again. (we have never had that issue before) It seems like if the value is below the threshold "1", it will trigger the alert, but what would be the cause of that? What components are factored in for the calculation?

Time Aggregation	Average
Time Aggregation	Average
Period	Over the last 5 mins
Value	0.857143
Operator	LessThan
Threshold	1
Criterion Type	StaticThresholdCriterion

Answer 1

@Admin Henrick welcome to the Microsoft Q&A community.

It looks like your alert was triggered because the availability metric dropped below the threshold of 1, with an average value of 0.857143 over the last 5 minutes. There are several potential causes for this:

1. Network Latency or Temporary Outages – Short-lived disruptions in connectivity can cause a momentary dip in availability.
2. Resource Exhaustion – If CPU, memory, or disk usage spikes beyond limits, the VM may become unresponsive for a brief period.
3. Underlying Host Issues – If your VM runs on a cloud provider's infrastructure, it could experience temporary host maintenance or hardware failures.
4. Application-Level Problems – Software crashes, misconfigurations, or performance bottlenecks might impact availability.
5. External Dependencies – If your VM relies on external storage, databases, or APIs, failures in those services might reduce availability.
6. Monitoring System Sensitivity – The aggregation method (average over 5 minutes) might capture minor fluctuations that wouldn't cause a complete outage.

To investigate further, I recommend checking system logs, performance metrics, and any recent changes that might have affected stability.

I hope these helps. Let me know if you have any further questions or need additional assistance.

Also if these answers your query, do click the "Upvote" and click "Accept the answer" of which might be beneficial to other community members reading this thread.

Answer 2

Admin Henrick I Hope you are doing well

Welcome to Microsoft Q&A Platform, thanks for posting your query here.

This usually indicates that availability dropped below 100% (which is interpreted as a full/healthy state = 1). A value of 0.857143 suggests that the VM was unavailable for a brief period within that 5-minute window

https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/windows/azure-vm-unavailable

Top common causes.

1. Host node maintenance or live migration
2. Temporary network issues
3. Disk latency or storage throttling
4. Guest OS crashes or hangs
5. High CPU or memory usage
6. Failed health probes
7. Incorrect alert configuration
8. Scheduled platform updates
9. Availability zone or set disruptions
10. Agent failures (e.g., Azure VM agent)
11. OS-level kernel panics or reboots
12. Incomplete startup during boot
13. Misconfigured extensions or daemons
14. Unplanned VM redeployments
15. Security patching or compliance restarts

Here is the official information about metrics and troubleshooting https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/windows/inaccurate-vm-availability-during-vm-restart?context=%2Ftroubleshoot%2Fazure%2Fvirtual-machines%2Flinux%2Fcontext%2Fcontext

Hope this helps.

If the suggested response helped you resolve your issue, please 'Accept as answer', so that it can help others in the community looking for help on similar topics.