How to Choose Data Center Racks / Cabinets

With the rise of colocation, enterprise and edge data centers, the requirements for data center racks have changed from being a cabinet that manages equipment to a rack enclosure that can reduce data center operational costs by preserving valuable floor space, optimizing cooling and increasing the efficiency of IT staff.

There are 6 considerations before choosing a data center rack:-


1) Weight Loads

Today's organizations need data center cabinets that can hold heavier loads and maintain their structural integrity when shipped with equipment. This could mean shipping from their facility directly to a data center, or shipping from an off-site integrator directly to their data center. Shipping a fully-populated rack allows for a faster data center build-out. The raised floor and the maximum floor loading should be considered as well.


2) Open Framed or Closed Frame

Open frame racks typically cost about one third as its equivalent counterpart in a closed frame option. There is nothing to obstruct airflow from circulating through the rack for cooling. But all your equipment is exposed making it susceptible to theft. Your servers' buttons or wires may also accidentally get pulled or pushed.

 

On the other hand, the process of installing or maintaining equipment is trickier for the closed fram racks due to the obstructed nature. If you choose to use this type of rack, sliding rails and shelves for severs and other equipment is highly recommended.

3) Sizing and Capacity

Server racks are sized in units classified as "U" space. Each U represents 1.75". So, a server rack that is 58U is 101.5" tall. The rack height is significant for how much equipment that can be held inside, as well as how much power can be transmitted to equipment in the server storage device. Some organizations may require more space between the server rack and the ceiling for cooling and cabling matters.

Your data center business grows fast. Leaving racks' space for few years later is a good planning for data center expansion.


4) Off-site Integration Processes

Racks should provide the flexibility to accommodate equipment from multiple vendors in a company’s supply chain, and the equipment needs of its data center environment. Many standard cabinets make it difficult to meet these needs, and many companies are turning to custom cabinets to increase overall flexibility and maximize efficiency in their off-site integration process.


5) Multi-vendor IT Environments

Racks need to provide maximum usable space, adequate clearances for airflow, easy access for troubleshooting and reconfiguration of equipment by IT staff and minimize air mixing.


6) The Rising Cost of Cooling

Cooling can be one of the top costs in today’s data center and reducing cooling costs, which can begin at the rack level, can play a major role in reducing overall energy consumption. More powerful equipment and greater data center densities have increased the heat generated in each rack, causing computer room air conditioning (CRAC) units to work harder than ever.

For example, the closed frame racks isolate heat sensitive equipment inside the frame. You have more control over where that air flows with the addition of fans and cooling accessories designed for closed frame racks. Therefore, it is critical to have a rack that supports optimized cooling efficiencies.



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For other design considerations / topics in data center and critical infrastructure, please visit 


(1) Site Selection,
(2) Space Planning,
(3) Cooling,
(4) Redundancy,
(5) Fire Suppression,
(6) Meet Me Rooms,
(7) UPS Selection,
(8) Raised Floor,
(9) Code & Standards,
(10) Transformers and Harmonic Distortion,
(11) Multi-mode UPS Systems,
(12) Electrical Rooms,
(13) Generator Systems,
(14) Generator Fuel Systems, 
(15) Battery Systems,
(16) Earthing / Grounding and Bonding, etc.

 
   

Data Center Design Consideration: Cooling

Further to the previous articles in Data Center Design Consideration: Space Planning, thermal management is also an important consideration in data center design. As more cloud-based platform and applications developed and the big data trends, the demand for server usage and data storage will grow continuously. As a result, more power is consumed and more heat is generated by the servers and electronics. Proper heat dissipation techniques are therefore necessary to ensure heat is effectively removed from the equipment.

Proper design for data center cooling at least has 3 components:


Mechanical, Ventilation and Air-conditioning (MVAC) Precision System

It supplies and distributes chilled air into the computer room. The MVAC system is designed based on the total heat load of the equipment. Depending on the geographical location of your data center, temperature is typically kept between 20 - 25 degree.

Rack Layout

The TIA-942 standard recommends the use of a hot aisle and cold aisle layout in positioning racks. Racks are organised in rows with an aisle dividing each row of racks. Racks are then installed with either the front or the rear of the rack facing each other along every aisle.

The aisles, which access the front, are designated cold aisles while the aisles that access the rear are designated hot aisles.

With this layout, cooled (fresh) air is introduced into the cold aisles. As the cooled air enters the rack and moves from the front to the rear, it extracts heat from the rack-mounted equipment. At the rear, air is expelled into the hot aisles where they are directed back to the Air Handling Units (AHU) / Computer Room Air-conditioning (CRAC) Units. Using this directed path of air circulation, the computer / servers equipment are effectively cooled.



Source: http://macc.umich.edu


Rack Design

In order to make the cool aisle / hot aisle layout effective, the rack are required to be carefully installed and designed. It ensures cooled air enters the rack, is forced through the equipment and hot air is expelled from the rack:

1. Intelligent fan doors for drawing cooled air into the rack.
2. Blower fans to ensures cooled air is available along the front of the entire rack.
3. Fan doors and blower fans are used when there are insufficient air entering the cabinet.
4. Filler panels and air dams for blocking gaps between the front and rear of the rack.
5. Air diverter kits to divert cooled air upwards which helps air to flow into the equipment and to prevent hot air at the back from re-circulating to the front.

About SMA

Strategic Media Asia (SMA), a critical infrastructure training and event organizer based in Hong Kong, provides an interactive environment and opportunities for members of IDC industry and engineers to exchange professional views and experience on critical infrastructure and E&M facilities.

SMA is one of the CPD Course Providers of the Chartered Institution of Building Services Engineers (CIBSE).

For details of other data center courses and seminars, please visit our website at http://www.stmedia-asia.com/trainings.html.

Data Center Design Consideration: Space Planning

A data hall houses computers and communications equipment that delivers, store and process information. This is the heart of the data center that operates all mission-critical applications. You need to address 2 key considerations:


(1) Restricting Access

Access to the data hall shall be limited and restricted to only authorized people and to minimize any accidental damage to the computer systems.

(2) Maximizing Floor Space

Floor space in the data hall is extremely valuable due to the high investment placed into the supporting infrastructure. It includes precision air-conditioning, standby power supply, equipment-safe fire protection system as well as security and monitoring systems.



"Non-essential" Items

Sometime "non-essential" doesn't mean useless. To maximize the use and enhancing the security of the area, "non-essential" items should be located outside the data hall. Examples of these items are:


(A) Operating Console / Network Operation Center (NOC)

It houses computer stations connect to the equipment or critical facilities in a data center. NOC may be situated in a separated room / area next to the data hall. Staff can monitor and manage the various systems here and enter the data hall only when they install cables or equipment. It also ensures that the operations and maintenance of the console do not affects the racks/cabinets inside the data hall.

(B) Gas Suppression Systems

Gas Suppression Systems such as FM200 are frequently used in a data center for fire fighting purposes. Gas is used over water as they do not damage the data hall's equipment when discharging. Unlike water, gas should be stored in gas cylinders. Placing these cylinders outside the data hall would allow your technicians to serve them easier.

(C) UPS Batteries & Generators

Uninterruptible Power Supply (UPS), high voltage switchgear and Genset are critical to supply backup power and are usually isolated in different rooms / area:

• Batteries will discharge gas during charging.
• Batteries contain acid that may leak and damage equipment
• Prevention of fire
• For safety reason, only qualified electrical workers are allow to enter the room and serve the high voltage facilities

(D) Air Handling Units (AHU) / Computer Room Air Conditioners (CRACs) Units

It's commmon for a dedicated AHU / CRAC Units to be used in a data room which ensure air from other parts of the data center is not recirculated into the critical area. In addition to being bulky, the AHU or CRAC Units generates heat and maintenance issues. AHU / CRAC Units, therefore, are unsuitable to be placed inside a data hall. Should they be installed in a data hall, they should be placed along the hot aisles.

Maintenance Area

It is important equipment installed in a data center can be repaired or replaced easily without affecting normal operations. Unless we absolutely sure that rear access to the equipment is not required, no equipment should be placed along a wall such as switchgear.

A minimum space greater than the depth of the equipment is required in front or at the back of the equipment which allows

- New parts' installation
- Maintenance or repair
- Airflow (such as hot aisle or cold aisle design)

For racks, a minimum of 1m clearance is observed between racks. A 1.5m radius is usually kept at the end of cabinets / racks which facilitates the use of trolley to move heavy equipment into the aisles.



Raised Floors

Typical raised floor inside a data hall / NOC are 150mm to 300mm (or higher depends on the floor height or design request, you may refer to the international standard / advice in TIA-942 or Uptime Institute). A ramp is usually created at the entrance to bridge the different in heights. It also allows trolley to move heavy equipment. The gradient of a ramp should not be steeper than 1:12.

Per normal practices, power cables (high voltage) are usually put under the raised floor, whereas data cables are usually put inside a cable tray overhead.

Cable Routing

We suggest power cables are separated from data cables. It ensures that the power cables do not pose any electromagnetic interference (EMI) to the data cables. Per previous advice, power cables are laid under the raised floors, whereas data cables are laid overhead.

In addition, data and power cables should be entered a data hall (or other faciliities' rooms) at opposite ends of the area whenever possible to avoid too many cables on one side and EMI problem.

Layout of a data center should be designed to minimize the run of data or power cables. For example, power cables enters the data hall and are routed through

- Riser (Cable Entry)
- Electrical Distribution Box / PDU (Power Distribution Units)
- UPS (High Voltage Switches, etc.)
- Equipment Racks

with minimized distance if they are located near each other relatively.

Expansion

Data Center are used to serve enterprises, government or other organizations. As business or services developed, the demand for faster applications and data storage grow as well. You are advised to allow space for expansion purposes. This expansion space could be located near the entrance of a data center / data hall which allows easier renovation and the installation of new equipment , cabinets and racks.

Cabling, cable trays and empty racks, where feasible, can be pre-installed in the expansion areas. This would minimize the amount of work to be done and the disruption of data center operations / equipment during expansion.



About SMA

Strategic Media Asia (SMA), a critical infrastructure training and event organizer based in Hong Kong, provides an interactive environment and opportunities for members of IDC industry and engineers to exchange professional views and experience on critical infrastructure and E&M facilities.

SMA is one of the CPD Course Providers of the Chartered Institution of Building Services Engineers (CIBSE).

For details of other data center courses and seminars, please visit our website at http://www.stmedia-asia.com/trainings.html.