Dual-Corded Power and Fault Tolerance: Past, Present, and Future
Uptime Institute Journal · Kevin Heslin
Uptime Institute Journal article tracing Uptime's Fault Tolerant Power Compliance Specification and why dual-corded IT underpins Tier III and IV.
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Overview
This 2014 article traces Uptime's Fault Tolerant Power Compliance Specification (2000, version 2.0 in 2002) and explains why dual-corded IT is the basis of Tier III and IV. Uptime defines critical distribution as everything from the UPS output through PDUs, panels, RPPs and whips or busway to the rack.
According to the article, more than half of the 5,000+ incidents in the Abnormal Incident Reports database relate to critical distribution. Analysis of 2007-2012 showed over 90% reduction in critical-distribution failures affecting IT load as dual-corded devices spread. Tier III and IV require a dual-corded architecture with active-active dual-path distribution.
The article also warns that a large static transfer switch (STS) is no substitute for true dual paths: a single large STS or STS-PDU does not meet Tier III/IV, and one STS-PDU fault took down a third of a site's IT and made the whole data center unavailable. The document is an industry opinion and analysis piece and does not replace the Tier Standard itself.
Key points
- Uptime defines critical distribution as everything from the UPS output through PDUs, panels, RPPs and whips or busway to the rack.
- More than half of 5,000+ incidents in the Abnormal Incident Reports database relate to critical distribution.
- AIRs analysis 2007-2012 showed over 90% reduction in critical-distribution failures affecting IT load as dual-corded devices spread.
- Tier III and IV require dual-corded architecture with active-active dual-path distribution.
- A single large STS or STS-PDU does not meet Tier III/IV.
- One STS-PDU fault took down a third of a site's IT and made the whole data center unavailable.
- The specification dates from 2000, with version 2.0 in 2002.
Using it in design
- In Tier III/IV templates, route two independent active paths from UPS output to each rack.
- Flag designs that depend on a large STS/STS-PDU as the only path diversity.
- Track 'cordCount' per IT device.
- Require a rack ATS only for single-corded loads.
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Who should read it
Electrical engineers and architects designing power distribution at Tier III and IV level.
Related standards
- Uptime Institute Tier Standard: Topology
Publication details
- Authors
- Kevin Heslin
- Publisher
- Uptime Institute Journal
- Year
- 2014
- Document language
- English
- Source type
- Industry body
- Access
- Free to read
- Licence
- Copyright retained; citation only — the publisher’s terms apply to the original document
Citation
Kevin Heslin (2014). Dual-Corded Power and Fault Tolerance: Past, Present, and Future. Uptime Institute Journal. https://journal.uptimeinstitute.com/dual-corded-power-details-change-theme-remains/
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