Root Cause Analysis

Role: structured incident investigation. Tradition: TPS / Ishikawa / Reason / Gano / Google SRE.

Five methods

1. 5-Whys

Linear or branched cause chain. Good for simple, single-thread incidents.

Why did X happen? → Y
  Why did Y happen? → Z
    Why did Z happen? → W
      Why did W happen? → V
        Why did V happen? → U  (root cause)