What happens when every test passes, every light is green — and nothing moves?
This postmortem walks through a real-world fibre channel degradation that bypassed every monitoring tool we had. It didn’t fail loudly. It didn’t trigger alerts. It didn’t log errors or flip dashboards red.
It slowed.
Silently.
Invisibly.
Beneath thresholds.
Behind metrics.
Inside cables no observability stack was ever designed to interrogate.
The system remained “healthy” by every formal measure — link lights green, keepalives intact, fabric negotiated. But throughput dropped to zero. Jobs stalled. I/O flatlined. And none of the tooling knew why.
The link was up. The system was green.
But nothing was moving.
That’s not just failure — that’s deception. A system that convinced every component it was functioning — and lied.
And in that moment, leadership wasn’t about fixing fast.
It was about seeing clearly.
Holding the line. Following the trace. And refusing to trust a system that insisted it was fine — while everything around it stalled.
This wasn’t just a hardware issue. It was a systems thinking crucible — where the real challenge wasn’t technical, but diagnostic.
Would we act on absence? Or wait for a failure that never came?
Have you experienced degradation that dodged every alarm?
I’m always open to comparing notes with other engineers and leaders who’ve navigated platform stillness, rootless bugs, or high-stakes recovery. Reach out — not for a pitch, just perspective.
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