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TIA-942Data Center Standards Overview

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TIA-942Data Center Standards Overview

B.For the past 20 years, cabling standards have been the cornerstone ofensuring proper design, instal lation, and performance of the net work . TheTelecommunications Industry Association (TIA) revolutionized our industry whenthey released the first TIA-568 Commercial Building Telecommunications WiringStandard, which describes the design, installation, and performance requirementsfor telecommunications cabling systems in commercial buildings. On the whole,standards have enabled our industry to effectively advance faster and further.Unfortunately, data centers were historically designed in the absence of establishedstandards. This had many network administrators faced with the challenge ofchoosing technologies and deciphering how to properly implement them into anoften-undersized space that is responsible for securely and reliably providing all theexisting and future services to an enterprise.In April 2005, th e TIA responded with the TIA-942 TelecommunicationsInfrastructure Standards for Data Centers, the first standard to specifically addressdata center infrastructure. Intended for use by data center designers early in thebuilding development process, TIA-942 covers the following:

Site space and layout Cabling infrastructure Tiered reliability Environmental considerations

This paper describes the key elements of the TIA-942 standard, a valuable tool indesigning your data center and maximizing your investment.


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TIA-942 Data Center Standards Overview

Site Space and LayoutProper space allocation fo r a data center starts withensuring that space can be easily reallocated tochanging environments and growth. Designers muststrike a balance between acceptable initial deploymentcosts and anticipated space required in the future.The data center should be designed with plentyof flexible "white space," empty space that canaccommodate future racks or cabinets. The spacesurrounding the data center must also be considered fo rfuture growth and planned fo r easy annexation.A large part of TIA-942 deals with facility specifications.The standard recommends specific functional areas,which helps to define equipment placement based onthe standard hierarchical star topology design fo r regularcommercial spaces. Designing a data center with thesefunctional areas anticipates growth and helps createan environment where applications and servers canbe added and upgraded with minimal downtime anddisruption. According to TIA-942, a data center shouldinclude the following key functional areas:

On e or Mo re Entrance RoomsThis is th e location fo r access provider equipmentand demarcation points, as well as the interface withcampus cabling systems. The Entrance Room may belocated either inside or outside the computer room, theportion of the data center that houses data processingequipment. The standard recommends locating th eentrance room outside of the computer room fo r bettersecurity. When located within the computer room, theEntrance Room should be consolidated with the MDA. Itis possible that provider's cabling distances may requiremultiple Entrance Rooms fo r larger data centers.

Main Distribution Area (MDA)Similar to an MDF, th e MD A is a centrally located areathat houses th e main cross-connect as well as corerouters and switches fo r LAN and SAN infrastructures.The MD A may inc lude a horizontal cross-connect(HC) fo r a nearby equipment distribut ion area. Thestandard requires at least one MD A and specifiesinstalling separate racks fo r fiber, UTP, and coaxialcable in this locat ion.

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One or Mo re Horizontal Distribution Areas(HDA)Similar to a TR, th e HDA serves as th e distribution

p o in t f o r horizontal cabling and houses cross-connectsand active equipment fo r distributing cable to theequipment distribution area. Like the MDA, thestandard specifies installing separate racks fo r fiber, UTP,and coaxial cable in this location. It also recommendslocating switches and patch panels to minimize patchcord lengths and facil itate cable management. TheHDA is limited to 2000 connections, and the numberof HDAs is dependent on the amount of cabling andoverall size of the data center.

Equipment Distribution Area (EDA)Horizontal cables are typically terminated with patchpanels in the EDA, th e location of equipment cabinetsand racks. The standard specifies install ing racks andcabinets in an alternating pattern to c r e at e " h o t "and "cold" aisles, a configuration that effectivelydissipates heat from electronics (see EnvironmentalConsiderations fo r a discussion on cooling and ho taisle/cold aisle configuration).

Zone D i str i b ut i o n A r ea (ZDA)The ZDA is an optional interconnection point in thehorizontal cabling between the HDA and EDA. The ZDAcan act as a consolidation point fo r reconfigurationflexibility or fo r housing freestanding equipment likemainframes and servers that cannot accept patch panels.Only one ZDA is allowed within a horizontal cabling runwith a maximum o f 288 connections. The ZDA cannotcontain any cross-connects or active equipment.

Backbone an d H o ri zon t al C ab l in gWithin the data center, backbone cabling providesconnections between MDA, HDAs, and EntranceRooms while horizontal cabling provides connectionsbetween HDAs, ZDA, and EDA. Optional backbonecabling can be installed between HDAs fo r redundancy.Each functional area must be located in such a wa y toprevent exceeding maximum cable lengths f or b ot hbackbone and horizontal cabling.

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Cabling

mputerRoom

Carriers - Entrance Room f--- Carriers(Carrier Equip &

Offices, Demarcation)Operations Center,Support Rooms ~ - - - - - - - - - - - - - - - - - - - -- - - - - - - - - -

IHorizontal Cabling: Backbone Cabling Co1

Telecom Room 1 Main Dist AreaIBackbone (Routers Backbone(Office & Operations Cabling LAN/SAN Switches,Center LAN Switches) 1 PBX, M13 Muxes)1v i- - - - - - - - - - - __ IHoriz Dist Area(LAN/SAN/KVM Backbone CablingSwitches)IHorizontal Cabling Horiz Dist Area Horiz Dist Area(LAN/SAN/KVM (LAN/SAN/KVMZone Dist Area Switches) Switches)I Horizontal Cabling IHorizontal Cabling I HorizontalEquip Dist Area Equip Dist Area Equip Dist Area

(Rack/Cabinet) (Rack/Cabinet) (Rack/Cabinet)

Figure 1. TIA-942 Compliant Data Center Showing Key Functional Area

Cabling InfrastructureBuilding on existing TIA-568 and 569 standards, theTIA-942 standard specifies a generic, permanenttelecommunications cabling system and providesspecifications for the following recognized cabling media: Standard singlemode fiber 62.5 and 50fJm mul timode fiber Laser-optimized 50fJm multimode fiber (recommended) 75-ohm coaxial cable (recommended for E-1, E-3, andT-3 circuits)

4-Pair Category 6 UTP and ScTP cabling (Cat 6*recommended)*NOTE: Augmented Category 6 was no t a released standardat t he t im e t ha t TIA-942 was rat ified. It is expected that futurerevisions of TIA-942 will specify Augmented Category 6 as thepreferred UTP cable fo r data centers.

For horizontal cabling, th e TIA-942 standardrecommends installing the highest capacity mediaavailable to reduce the need for re-cabling in the future.While Category 6 is the highest horizontal cablingmedia recognized by the standards today, verif ied10 Gigabit Ethernet over UTP solutions are availableand standards are in development. ADC believesserious consideration should be given to specifying anAugmented Category 6 solution fo r UTP-based datacenter infrastructures.The TIA-942 standard also specifies maximum backboneand horizontal cabling distances based on the cablingmedia and applications to be supported in th e datacenter. Backbone fiber optic cabling is typically limitedto 300m while horizontal copper cabling is limited to100m. However, fo r small data centers where th e HDAis combined with th e MDA, horizontal f iber cabling mayextend to 30 0 meters.

TIA-942 recommends th e use of laser-optimized 50fJmmultimode fiber fo r backbone cabling because of itscapability of supporting higher network speeds overlonger distances while being more cost-effective toimplement than singlemode fiber.

The TIA-942 standard provides several requirementsand recommendations fo r cabling management. Thedata center must be designed with separate racksand pathways fo r each media type, and power andcommunications cables must be placed in separate

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pathways or separated by a physical barrier. Adequatespace must be provided within and between racks andcabinets and in pathways for better cable management,bend radius protection, and access. For example, thestandard requires a minimum of 3 feet in rows (4 feetrecommended) and recommends aligning racks andcabinets on raised floors in a way that enables easylifting of tiles. Locating switches and patch panels toreduce the need for patching between cabinets andracks is also recommended.TIA-942 extends the TIA-606-A Administration Standardto data centers, which specifies a labeling scheme for allracks, cabinets, patch panels, patch cords, and cables.

Tiered ReliabilityTo provide a means for determining specific data centerneeds, the TIA-942 standard includes an informativeannex with data center availability tiers. These tiersare based on information from the Upt ime Insti tute,a consortium dedicated to providing its memberswith best practices and benchmark comparisons forimproving the design and management of data centers.For each of the four tiers, the annex describes detailedarchitectural, security, electrical, mechanical, andtelecommunications recommendations, and the higherthe tier, the higher the availability. Tier descriptions includeinformation like raised floor heights, watts per squarefoot, and points of failure. "Need," or "N," indicatesthe level of redundant components for each tier with Nrepresenting only the necessary system need. Constructioncost per square foot is also provided and varies greatlyfrom tier to tier; with Tier 3 costs double that of Tier 1.Breaking data center reliability into these tiers providesdesigners with a method for qualifying certain aspectsof the data center and objectively comparing one datacenter to another.

Tier 1- Basic: 99.671% Availability Susceptible to disruptions from both planned andunplanned activity Single path for power and cooling distribution, noredundant components (N) Mayor may not have a raised floor, UPS, or generator Takes 3 months to implement Annual downtime of 28.8 hours Must be shut down completely for perform preventivemaintenance

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Tier 2 - Redundant Components:99.741% Availability Less susceptible to disruption from both planned andunplanned activity Single path for power and cooling disruption, includesredundant components (N+1) Includes raised floor, UPS, and generator Takes 3 to 6 months to implement Annual downtime of 22.0 hours Maintenance of power path and other parts of theinfrastructure require a processing shutdown

Tier 3 - Concurrently Maintainable:99.982% Availability Enables planned activity without disrupting computerhardware operation, but unplanned events will still

cause disruption Multiple power and cooling distr ibut ion paths but with

only one path active, includes redundant components(N+1) Takes 15 to 20 months to implement Annual downtime of 1.6 hours Includes raised floor and sufficient capacity and

distribution to carry load on one path whi leperforming maintenance on the other.

Tier 4 - Fault Tolerant: 99.995% Availability Planned activity does not disrupt critical load and datacenter can sustain at least one worst-case unplanned

event with no critical load impact Multiple active power and cooling distr ibut ion paths,includes redundant components (2 (N+1), i.e. 2 UPSeach with N+1 redundancy) Takes 15 to 20 months to implement Annual downtime of 0.4 hours

Environmental ConsiderationsSeveral environmental considerations exist within theTIA-942 data center standard that are similar to theequipment room requirements set forth in previousTIA standards. These considerations include, butare not limited to, fire suppression, humidity levels,operating temperatures, architectural, electrical (power)and mechanical system specifications. Some of therequirements are dependent on the desired reliabilitytier described above. II.


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Power CoolingDetermining power requirements is based on thedesired reliability tier and may include two or morepower feeds from the utility, UPS, multiple circuitsto systems and equipment, and on-site generators.Determining power requirements requires carefulupfront planning.Estimating power needs involves determining thepower required for all existing devices and for devicesanticipated in the future. Power requirements mustalso be estimated for all support equipment suchas UPS, generators, conditioning electronics, HVAC,lighting, etc. The power estimation must be made toaccommodate required redundancy and future growth.

Most significantly, the standard incorporatesspecifications for encouraging airflow and reducing theamount of heat generated by concentrated equipment.The standard recommends the use of adequate coolingequipment as well as a raised-floor system for moreflexible cooling. Additionally, the standard states thatcabinets and racks should be arranged in an alternatingpattern to create "hot" and "cold" aisles. In the coldaisle, equipment racks are arranged face to face. In thehot aisle, they are arranged back to back. Perforatedtiles in the raised floor of the cold aisles allow cold airto be drawn into the face of the equipment. This coldair washes over the equipment and is expelled out theback into the hot aisle. In the hot aisle, there are noperforated tiles, which keeps the hot air from minglingwith the cold (see Figure 2).

Cabinets

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Cabinets

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Cabinets

TelecomCable Trays Power Cables00000

TelecomCable Trays Power Cables00000

Figure 2. Hot Aisle/Cold Aisle Cooling

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Because not every active piece of equipment exhaustsheat out the back, other considerations for coolinginclude the following: Increase airflow by blocking unnecessary air escapesand/or increasing the height of the raised floor Spread equipment out over unused portions of theraised floor, space permitting Use open racks instead of cabinets when security isnot a concern, or use cabinets with mesh fronts andbacks Use perforated tiles with larger openings

ConclusionWhen i t comes to bui lding a rel iable data center andmaximizing your investment, the design must beconsidered early in the building development processand include coordinated efforts that cut across severalareas of expertise including telecommunications, power,architectural, and HVAC.Each of the components of the data center and itssupporting systems must be planned, designed, andimplemented to work together to ensure reliableaccess of data center resources while supporting futurerequirements. Neglecting any aspect of the designcan render the data center vulnerable to cost failures,early obsolescence, and intolerable availability. Thereis no substitute for careful planning and following theguidelines set forth in the TIA-942 TelecommunicationsInfrastructure Standards for Data Centers.

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To obtain a copy of the TIA-942 standard or to receivemore information, visit the following websites:

For Information onTIA-942 StandardVisit The TIA at:wwwtiaonline.org/standards

For information onGeneral data center reliabilityinformation including powerand coolingVisit The Uptime Insistute at:wwwupsite.com

For Information onComponents and Best PracticesVisit ADC at:wwwadc.com

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II. Web Site: www.adc.comFrom North America, Call Toll Free: 1-800-366-3891 Outside of North America: +1-952-938-8080Fax: +1-952-917-3237 For a l isti ng of ADCs global sales office locations, please refer to our web site.ADC Telecommunications, Inc, PO Box 1101, Minneapolis, Minnesota USA 55440-1101Specifications published here are current as of the date of publication of this document. Because we are continuouslyimproving our products, ADC reserves the right to change specifications without prior notice. At any time, you mayverify product specifications by contacting our headquarters office in Minneapolis. ADC Telecommunications, Incviews its patent portfolio as an important corporate asset and vigorously enforces its patents. Products orfeaturescontained herein may be covered by one or more U.S. or foreign patents. An Equal Opportunity Employer102264AE 1/06 Original 2006 ADC Telecommunications, Inc. All Rights Reserved

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