What is the amount of fuel that should be on hand to power generators for backup datacenter power, in all tiers, according to the Uptime Institute?

'1' is an arbitrary number and does not correspond to any standard for generator fuel.

'1,000 gallons' is a specific volume that may or may not be sufficient for 12 hours, depending on generator size and load, and is not the universal metric used by Uptime Institute.

The Uptime Institute's Tier Standard for Data Center Availability specifies that all Tier-certified data centers, regardless of Tier level (I, II, III, or IV), must have a minimum of 12 hours of on-site fuel storage for their generators. This ensures a baseline duration of backup power in the event of a utility power failure, supporting continuous operations or an orderly shutdown.

While ensuring graceful shutdown is important, the Uptime Institute standard specifies a concrete duration (12 hours) for sustained operation, which goes beyond just facilitating a graceful shutdown, implying continuous operation capabilities.