Developed by The Uptime Institute, the Tier Classification and Performance Standard defines four levels of availability for a complete site, ranging from the basic Tier l to Tier lV, which describes the highest possible data processing availability (more here).
Tier classification does not refer to a certain tecnology or design, it is a methodology used to determine availability in a facility. It’s up to the operator how he achieves the goals.
But as Alan Luscombe, director at Uninterruptible Power Supplies Ltdwrites, writes in a recent article, the Tier Classification offers some key guidelines for power system specifications:
„They include the UPS’s need to protect from power spikes and sags as well as momentary power failures, plus the requirement for an engine generator to cater for longer-duration outages. Redundancy, modularity and the ability to perform maintenance and repairs without shutdown also become essential for higher tiers.“