Tier Myths and Misconceptions

Uptime Institute answered questions submitted during the "Intro to Tiers Classification System Webinar" in the new Tier Program email series.

Q: Will the runtime limitations of the generators mandated by Air Permits affect the tier rating requirements?

A: There is no correlation between the EPA [Environmental Protection Agency] Tiers (or other restrictions of engine-generator operation) and Uptime Institute Tiers. We acknowledge that this has both design and operations considerations and consequences, but we caution comparison or linking of the two systems, despite use of similar terms.

Q: Does an inline ATS [automatic transfer switch] meet the requirement for dual paths to a server  (i.e., the server has one cord from the server to the ATS, but the ATS (think rack mount) has dual power feeds)?

A: Tiers provides a concession for equipment with odd numbers of cords (1,3,5) in the form of rack-mounted transfer switches to provide access to multiple power paths.

Q: Does Tier Certification only apply to newly built facilities?  Can we get an existing facility certified?

A: We have Certified existing buildings. There are some challenges inherent to the process as there is live load. We urge that the process begin with a Tier Gap Analysis rather than a formal Certification effort. Tier Gap Analysis provides a summary-level review for major Tier shortfalls (if any). This allows the owner to make an informed decision whether to proceed with a detailed, exhaustive Certification effort.

Q: If we applied for Tier IV, and it was found we deserve Tier III, do we still get Certified as Tier III or just not Certified because we had not applied for it?

A: It is possible. The first work in a Tier Certification effort is to work with the client to establish a reasonable Tier objective. If Tier IV compliance is not feasible due to budget or pre-existing infrastructure, then the focus will revert to the appropriate Certification level.

Q: How does EPO [emergency power off] (or other systems that are required by code that shut down the critical load) affect Tier Classifications?

A: When code or local jurisdiction mandates an EPO, this does not necessarily prohibit Tier compliance. We do require demonstration that maintenance can be performed on the EPO system without affecting the critical load. Beyond Tier, it is Uptime Institute’s recommendation that EPOs be avoided whenever possible, as they are a proven cause of data center downtime through accidental activation. And they are other means of providing the intended life-safety benefits without posing a risk to ongoing uptime.

Tiers is not a one size fits all, but allows for many ways to meet the criteria. You and your team determine the best solution for your project.

Uptime Institute encountered the following Tier Myths and Misconceptions, published on 24 March 2010, during recent site visits in Latin America, Europe, Russia, Africa, and Asia. These myths have taken attention away from the fundamental concepts of the Tier Classification System. The result has been shortfalls in design topology despite adequate budgeting. These shortfalls put the data center's ongoing uptime at risk. Although encountered more often internationally, the myths below have also been noted in North America.

Myth:TIA-942 is a guideline for Uptime Institute Tiers.

Uptime: The similarities between the Uptime Institute Tiers and TIA-942 stop at the surface. Uptime Institute Tiers is functionally disconnected from TIA-942. The core objective of Uptime Institute Tiers is to guide a design topology that will deliver high levels of availability -- as dictated by the owner's business case. Uptime Institute Tiers evaluates data centers by their capability to allow maintenance and to withstand a fault. Uptime Institute Tiers is not available in checklist form. To avoid further confusion, Uptime Institute recommends Roman numbers (I, II, III, IV) to signify Tier-based projects.

Myth:Uptime Institute Tiers is U.S.-centric.

Uptime: The Uptime Institute is currently delivering Tier Certifications in over 25 countries. During the design and construction of these projects, there has not been a conflict between Tiers and local building codes, statutes, or jurisdictions. Tiers, which allows for many solutions and a variety of configurations, gives the engineering and operations team the flexibility to meet both the local regulations and the performance requirements.

Myth:Uptime Institute Tiers requires an EPO.

Uptime: Analysis of the Uptime Institute's Abnormal Incident Report database reveals that accidental EPO activation is a recurring cause of downtime. Uptime Institute Tiers does not mandate an EPO. Unless compelled by a local jurisdiction or code, Uptime Institute does not recommend EPO installation. However, if an EPO is installed, it must also incorporate the Concurrent Maintainability or Fault Tolerant objectives, as specified by the owner.

Myth: Uptime Institute Tiers requires raised floor.

Uptime: The choice of underfloor or overhead cooling is an owner decision based an operational preference. In Uptime Institute experience, a raised floor enhances operational flexibility over the long term. Yet, decisions such as raised floor or on-slab, Cold Aisle/Hot Aisle, containment of Cold/Hot Aisles, and gallery cooling can affect the efficiency of the computer room environment, but are NOT mandated by Uptime Institute Tiers.

Myth:For Tier III and IV, the engine-generator plant must be operational at all times.

Uptime: Data centers will utilize the public electrical utility a majority of the time. However, the engine-generator plant must be properly configured and sized to carry the critical load without runtime limitations. Meeting this criteria requires special attention to the engine-generator capacity ratings and the feeds to the engine-generator plant. In all cases, Uptime Institute Tiers does not require that the engine-generator plant run at all times.

The Uptime Institute has recently released two Accredited Tier Designer Technical Papers. These papers, part of an ongoing series, provide technical clarity on the Tier consequences of specific subsystems. The topics, makeup water source and engine-generator ratings, were identified as areas of concern by attendees from over 13 countries at the 2010 Accredited Tier Designer sessions.

The Accredited Tier Designer Technical Paper Series and Tier Standard: Topology is available in our Research & Publications section.

The following Tier Myth and Misconception, published on 29 October 2009, addresses the commonly held belief that Tier dictates infrastructure physical security. Tier requirements address the functionality of the data center design topology; Operational Sustainability addresses the risk factors beyond design topology, including infrastructure physical security.

Myth:Re-enforced perimeter fencing is required for Tiers III and IV.

Myth:Physical security measures for outdoor critical equipment (e.g., fuel storage tanks) are a Tier requirement.

Myth:CCTV is required for Tiers III and IV.

Uptime: The Tier Classification System does not prescribe security provisions. Nevertheless, these infrastructure physical security risk factors should be specifically and thoroughly addressed in the owner’s Operational Sustainability requirements.

The level of security is largely determined by industry, the criticality of the IT function performed on site, and the owner’s policies. For example, a financial institution will typically invest in a level of security exceeding that of an academic institution.

There are numerous infrastructure physical security measures which are best practices, regardless of Tier. These include biometric readers, bollards, guard houses, hiding in plain sight, mantraps, re-enforced perimeter fencing, video surveillance, etc. Best practices are critical in reducing the risk exposure of curiosity, mischief, crimes, and accidents. However, best practices should not be confused with Tier requirements.

In order to maintain focus on the Tier requirements, the Uptime Institute has published Tier Standard: Topology, which places the Tiers in a standards format to facilitate practical application. This document puts aside the attributes and illustrations that can lead to confusion. Tier Standard: Topology is available for download.

The following three myths, published on 21 September 2009, finish the discussion begun by Digital Realty Trust's video "Myth of the Month: The Tier System."

Myth:Tiers do not address business requirements.

Uptime: The Tiers are a performance-based, business-case-driven data center benchmarking system. An organization's risk tolerance determines the appropriate Tier for the business. In other words, the Tiers are predicated on the business case of the individual company. Without determination of a unique business case, organizations are misusing the Tiers and bypassing the internal dialogue that needs to occur.

Myth:Tier II provides Concurrent Maintenance opportunities.

Uptime: Tier II ensures redundant capacity components, but requires a shutdown of the computer room for planned maintenance or replacement of critical equipment. The fundamental concept of Tier III is Concurrent Maintenance functionality. Digital Realty Trust asserts the following: "Concurrent Maintainability is actually one of the most important driving design characteristics that you need to have inside your data center. You need to be able to maintain your facility while it's running, regardless of if it's a Tier IV to a Tier II design." Digital Realty Trust mentions Tier II and IV solutions, but disregards Tier III. The requirement to maintain infrastructure without shutting down equipment, known as Concurrent Maintainability, defines Tier III. Many owners' business cases, including healthcare, domestic outsourcers, and state governments, require Tier III. The list of organizations that have protected their investment with Tier III Certification may be found HERE.

Myth:Nobody needs a Tier IV data center.

Uptime: Many owners' business cases require Tier IV, including banking/financial; insurance; outsourcers in UK, Middle East, and South Africa; and federal and provincial governments. (List of Tier IV Certifications may be found HERE.) The Tiers are not prescriptive. Tier IV is not the best answer for all organizations, neither is Tier II . Experience dictates that owners perform due diligence assessments of their own and outsourcers' facilities to address the following: If the facility is Tier II and by definition does not include Concurrent Maintenance capabilities across all critical subsystems, a) can the business tolerate a maintenance-related shutdown and b) how does the site operations team propose to coordinate a maintenance-related, site-wide shutdown across 10s or even 100s of data center clients?

The following four myths were published on 27 August 2009.

Myth:Utility Feeds

Uptime: The number of utility feeds, substations, and grids that provide public power to the facility neither predicts nor influences Tier.

Myth:Component Count

Uptime: N+1, N+2, S+S, or 2(N+1) does not determine Tier.

Myth: TIA-942

Uptime: Tier Certification is a third-party, independent assessment to the Uptime Institute's Tier Classification System, performed by its Professional Services consultants.

Myth:Site Location

Uptime: Although a critical consideration for the lifecycle operation of the facility, geographical location does not affect Tier.