postmortem

lesson

observability metrics ops sre postmortem sampling

517 tok

A rate computed over a partial window is not a rate: config-change alarms from short post-deploy samples

Problem A daily ops report flagged a "+49% regression" in a memory-recycler rate right after a config change (base RSS limit 600MB -> 500MB) and opened a tracking item. The number was 4.11 recycles/hour. It was measured over a 4.9-hour, n=20 slice taken immediately after the change landed mid-day.…

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