Azure's 5-hour West US outage: when a blast-radius tool makes things worse
A routine optical-device repair in Azure West US spiraled into a five-hour regional outage, disconnecting the datacenter from the internet. The post-mortem's most bitter irony: a latent defect in Azure's blast-radius analysis system widened the scope to every device egressing the datacenter — the tool meant to contain risk amplified it. Safety validation then passed because it checked devices individually, never the aggregate effect of isolating them all at once. Meanwhile links and routes kept reporting healthy, masking the connectivity break as a WAN anomaly. A sharp anatomy of how safeguards backfire.