Facility ratings.
WHAT THEY DESCRIBE
The level of redundancy and maintainability in a facility's infrastructure.
WHAT THE LEVELS BROADLY REPRESENT
Basic capacity, with single paths Redundant components, still on a single path Redundant components with multiple paths, allowing maintenance without interruption Fault tolerance, surviving a failure without interruption
WHAT THE HIGHER LEVELS ADD
The ability to maintain any component without taking the facility down The ability to survive an unplanned failure
WHAT THAT MEANS PRACTICALLY
Lower levels require shutdown for maintenance.
WHAT TO BE CAREFUL WITH
Facilities describing themselves as a level without independent certification Claims about design rather than what was built Claims about the building rather than the specific hall
WHAT TO ASK
Whether the facility is certified, by whom, and for what.
WHAT ELSE TO ASK
Whether the certification covers design, the constructed facility, or ongoing operation.
Those are different.
WHAT MATTERS AS MUCH AS THE RATING
How the facility is actually operated.
WHAT TO REQUEST
Evidence, not description.
