Comparison
Configuration driftvsNormalisation of deviance
Configuration drift
one instance behaves differently from the others and nobody can say what was changed on it by hand eight months ago.
Divergence between the intended configuration and what is actually running, accumulated through manual fixes. It produces failures that reproduce on one node only and cannot be tested for. Infrastructure as code plus immutable deploys remove it by making the running state disposable.
Full entry →Normalisation of deviance
the deploy has warned about that for months and everyone knows to ignore it.
The process by which an unsafe practice becomes normal because it has not yet caused harm. Each individual acceptance is rational — it worked last time — and the standard drifts until the anomaly is invisible to the people inside it. It is the mechanism behind most large organisational failures, and the practical countermeasure is periodic outside eyes plus taking small deviations seriously while they are still small.
Full entry →