Hey everyone! 👋 I've been diving into Sentinel for a few months now and am really trying to get my data pipeline solid. I've hit a snag with the Azure Monitor Agent (AMA) and syslog forwarding that I'm hoping someone can help me unpack.
We're onboarding some on-prem Linux servers and using the AMA to forward syslog (auth.log, syslog, etc.) to a Log Analytics workspace. The setup seemed to go fine, but I'm seeing inconsistent logs in Sentinel. Sometimes there are huge gaps, or the logs just stop for a few hours before coming back. The DCR (Data Collection Rule) looks correct and matches the docs.
Has anyone else run into this? I'm specifically wondering:
* Are there known throttling limits or buffer issues with AMA for syslog that I might be hitting?
* Could it be a network or connectivity hiccup between the agent and the ingestion endpoint?
* Is there a best practice for monitoring the health of the AMA itself that's more detailed than just checking if the service is running?
I've checked the agent's extension logs (`/var/log/azure/Microsoft.Azure.Monitor.AzureMonitorLinuxAgent/`), and I see some occasional "transient errors" but nothing that clearly screams "this is why logs are dropped."
I'm still learning the Azure monitoring ecosystem, so any pointers on where to look next or a step-by-step troubleshooting guide would be amazing. Maybe a recommended query to see if logs are being dropped at the agent level? Thanks in advance — this community has been a huge help so far!
Yeah, I've seen gaps like that before with AMA on Linux. The "transient errors" in the extension logs are usually the clue. For me, it turned out to be a resource issue on a smaller VM - the agent would basically fall behind during high log volume and then try to catch up later. Have you checked the server's memory and CPU when the gaps happen?
Also, are you using TLS for the ingestion endpoint? I've heard network timeouts can cause weird hiccups if the connection isn't totally stable.
How are you checking the agent health now? I usually just ssh in and check the service status, but I'm guessing there's a better way.
Still learning
That's a great point about checking resource usage. The CPU spike during catch-up phases can be pretty deceptive. It might look fine when you check manually, but the spikes during log bursts can cause the exact gaps you're describing.
You mentioned checking service status via SSH. The agent's own health logs in /var/log/azure are usually more telling than just the service being "active." For a more centralized view, there's a built-in heartbeat signal you can query in Log Analytics. If you run a query for `Heartbeat | where Category == "Azure Monitor Agent"`, you can see if the agent itself is checking in, which can sometimes narrow down if it's a local resource issue or an ingestion problem.
Let's keep it real.