# Resilience, service and contract

Lesson 4 of [Evaluate a liquid cooling vendor before you buy](https://liquidcooling.fyi/academy/evaluate-a-liquid-cooling-vendor.md), 13 minutes.

A cooling failure can stop IT equipment fast. Ask how the system fails before you ask how it works. Resilience - Which redundancy model does the vendor propose for pumps, heat exchangers and controls: N+1, 2N or another? - How fast is the switchover when a pump or a CDU fails? Is it automatic? - Wha…

The rest of this lesson is for learners enrolled in the course. [See how Evaluate a liquid cooling vendor before you buy works](https://liquidcooling.fyi/academy/evaluate-a-liquid-cooling-vendor.md).

Also on the [web page](https://liquidcooling.fyi/academy/evaluate-a-liquid-cooling-vendor/resilience-service-and-contract).