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ITGlossary · UPS technology
Six Nines Availability
Availability of 99.9999%, about 32 seconds of downtime a year, which requires redundancy across the whole power chain.
Technical level:Advanced
Availability of 99.9999% corresponds to roughly 32 seconds of total downtime over an entire year. For comparison, three nines (99.9%) allow about 8.8 hours of downtime per year and five nines about 5 minutes.
Such a high level cannot be achieved with a single UPS, however reliable it is. It requires redundancy (for example N+1 or 2N), dual supply paths, a maintenance bypass, a generator and systematic monitoring. That is why it mainly concerns data centres, telecommunications and critical hospital applications.
When assessing such a requirement, look at the entire power chain: a single point of failure, such as a single distribution board, can cancel out all the redundancy.
Related terms
- RedundancyHaving more UPS units or modules than the load needs, typically in an N+1 or 2N configuration, so the load stays powered if one fails.
- Redundant Power SupplyA second power supply inside a server or switch that takes over without interruption if the first one fails or loses its feed.
- Modular UPSA UPS design where independent modules can be combined to meet power and redundancy needs.
- AC EfficiencyIndicates how efficiently a UPS converts incoming AC power into usable output power during normal operation.
- Auto RestartA UPS feature that automatically restarts the system after utility power returns following a shutdown.
- AutonomyThe time a battery-powered system (like a UPS) can continue operating critical loads after a power failure.