| Sun Microsystems Data Center Site Planning Guide |    
|
| Sun Microsystems Data Center Site Planning Guide |
|
| C H A P T E R 2 |
|
General Computer Room Criteria |
This Chapter details the proper design and building of a computer room as indicated in the Sections that follow:
Proper planning of the data center does not end with its conception and construction. The computer environment is constantly evolving to accommodate changes in technology and the business landscape. Tools that help adapt to these changing needs are essential in a modern data center. Just as it is important to monitor of environmental conditions, it is also important to keep updated working drawings of the computer areas.
A computerized drafting system is an investment in the future of the data center. This allows for the continued updating of the electrical, mechanical and computer systems. Updated drawings can be used in site evaluation and future planning, and various scenarios can be explored in detail. The availability of accurate, updated plans also facilitates projects involving outside contractors. The maintenance of updated, computerized prints is highly recommended.
When designing the data center, it is important to include additional resources for redundancy. This may be in the form of available power, environmental support equipment or floor space. This redundancy allows for the flexibility necessary to accommodate changes and short-term growth associated with hardware upgrades. It also allows for uninterrupted operations during upgrades or replacements in hardware. New hardware can be run simultaneously with the hardware it is replacing, rather than swapping the two. Redundancy also allows security in the event of a failure. This is particularly true of the environmental support equipment.
While most data centers are designed with at least a minimal amount of redundancy, this issue is often forgotten in future planning. Excess floor space or support systems that were designed for redundancy, are often used for growth, reducing the protection they once provided. It is important to carry through this important factor in the future planning of the room. The redundancy must be maintained, even as the demands of the data center grow. The amount of redundancy planned can be increased in the design phases to address this. This will provide room for growth while still providing the back-up needed. If this is not done, the support systems should be increased along with the hardware during the expansions. Failure to provide adequate redundancy can lead to logistical problems and may degrade the overall reliability of the computer operations.
Each evolution in hardware technology dramatically increases the computing or data storage capacity per square foot of the room. This is how most data centers have been able to survive for so long without continually expanding their physical dimensions. The evolution of the computer room is normally a continuous process of minor growth and changes within a larger cyclical pattern of more dramatic changes. Hardware will normally continue to grow in the room until it nears capacity, then changes will be made to regain some of this floor space through upgrades in technology. The computer room will then begin to encroach on this newly available space as demands on the computer room continue to increase, and the cycle will repeat. In some cases the changes in technology and the increased needs for computing or storage capacity will evolve at the same speed, in other instances, one will out-pace the other.
When technology evolves more quickly than the needs of the business, the data center will normally develop open areas, devoid of hardware. These may remain for some time, and are often very attractive real estate to other areas of the business. It is important not to be too quick to down-size the data center areas, as properly designed hardware spaces are much more expensive to construct than typical office environments. All planning of expansions or reductions to the raised floor computer room areas must be considered in macro terms. It is often much more financially prudent to allow portions of a well-designed room to remain vacant than to try to reconstruct this from converted office space when the data center demands increase.
If the needs of the business outpace the evolution of the technology, it may be necessary to increase the physical dimensions of the data center. This should also be done in conjunction with long-term planning. Moving to more space efficient technologies, when available, may prove to be more cost effective than expanding the physical dimensions of the computer room.
Whether a design-built room, or a renovated area, the computer room must be able to accommodate diverse hardware designs and requirements. The mission of a computer room rarely remains stable, and the hardware designs and configurations change as technology and the goals of the company evolve. While the future of a computer room can rarely be anticipated, it is essential that the hardware areas are planned in such a fashion as to allow for seamless adaptation to the changing needs.
The main criteria driving the type of hardware in the room will be determined by the applications of the business. The following general guidelines should be used in planning the current layout of the Sun Microsystems hardware and support equipment, and to help in preparation for future changes.
Access to the computer rooms should be strictly regulated, and limited to only those personnel necessary for its operation. All personnel working within the data center should have at least a basic understanding of the sensitivities of the hardware so as to avoid activities that pose a direct risk to the hardware. Accidental contact with hardware buttons, cable connections, terminals or emergency response controls can all cause system interruptions of varying degrees.
All points of access to the computer rooms and other sensitive areas should be controlled by checkpoints or coded card readers to restrict access to authorized personnel. Security personnel should also remotely monitor points of entry via camera.
The raised access floor system provides the flexibility in wiring, hardware location and air conditioning. The raised floor should be constructed of 24 inches x 24 inches (61 cm x 61 cm) panels interchangeable with perforated tiles for air distribution or custom cut tiles for cable or utility passage. This design isolates data lines, power cables and piping to provide a safe environment for operators and to protect hardware operations. In addition, the raised floor design provides a means for flexible and efficient air distribution to the hardware. While it is possible to accommodate a small number of hardware units in alternately designed rooms, it is highly recommended that large numbers of hardware cabinets are installed in a raised floor system.
There should ideally be 24 inches (61 cm) between the raised floor system and the structural deck. A minimum of 18 inches (46 cm) should be provided. Variations from this figure should be based on air conditioner design and anticipated subfloor congestion. Inadequate subfloor depth will lead to difficulties in systems reconfiguration over time, may make the removal of unused or obsolete cables difficult, and will likely obstruct airflow. Additional space may be advisable if subfloor obstructions are abundant.
A raised floor system utilizing bolted stringers is recommended to provide the maximum rigidity for dynamic loads as well as to enhance the signal reference grid. Snap-on stringers often come loose affecting the integrity of the floor structure. While some stringerless systems claim the same benefits as bolted stringer systems, a great deal of research should be done prior to choosing an alternative to the recommendation. In addition, stringerless systems may require additional supports where custom cable cutouts are made for air or cable transfer. In addition, bolted stringer systems allow for the removal of adjacent tiles without threat to the integrity of the floor.
The floor tiles in the raised floor should be 24 inch x 24 inch (61 cm x 61 cm). The tile core may be constructed of compressed wood or concrete, or may be an open structural metal design. The entire tile should be constructed of, or encased in, galvanized or painted steel. Alternately, cast aluminum tiles may be used.
The tiles should have a high-pressure laminate top surface. The floor surface must allow for proper dissipation of electrostatic charges. The floor tiles and grid systems should provide a safe path to ground through the tile surface, to the floor substructure and through the signal reference grid. The top surface of the floor covering to understructure resistance should be between a minimum of 1.5 x 105 ohms and a maximum of 2 x 1010 ohms (as per NFPA 56A Test Method). The panel structure (not surface laminate) to understructure resistance should be less than 10 ohms.
Carpeted tiles should not be used in hardware areas. Carpeted tiles can harbor contaminants that are agitated every time the tile is walked on. In addition, these tiles are more easily damaged by the movement of hardware, or even when removed using specially designed tile lifters that incorporate spikes designed to catch the loops of the tiles. Carpeted tiles designed with static dissipative properties can become less effective in this regard as they wear over time. Carpeted tiles that are laid over an existing raised floor surface, are normally offset from the grid, and make it more difficult to access the subfloor. Carpeted tiles should only be used in command centers, or other that do not house sensitive hardware, and do not require frequent access to the subfloor void.
The tile surface should be maintained to the manufacturer's specifications. The guidelines listed in Section 4.2.6, Cleaning Activity" should be used. No waxes or insulative coatings should be used, as these can form a barrier that interferes with the static dissipative properties of the floor. It is also extremely important that the stringers and pedestal tops be kept clean, as a buildup of contaminants on these surfaces can potentially impact the functioning of the floor as well. Replace tiles as the surface becomes damaged, or as they become warped by heavy loads. A damaged surface or a tile that does not sit tightly in the grid can affect the ability of the tile to properly dissipate static charges, and could pose a safety hazard.
Tiles will need to be customized to accommodate the shape of the room, the air conditioners and the hardware. All tile modifications should be performed according to manufacturer recommendations. Additional structural support may be necessary where partial tiles are installed along walls, around columns or by air conditioners. The exposed cut edges of all cut-outs for cable or air passage should be capped with protective trim. Exposed metal edges can damage cabling, and the exposed cores of some tiles can shed particulate matter into the airstream.
The load capacity of the structural floor must be taken into account when designing the data center. Some areas designed for light duty, such as office, may be inadequate. A qualified structural engineer should be consulted in the evaluation of potential areas for the location of a new data center within an existing building. Enhanced support may be advisable in high traffic areas, or areas with heavier than normal loads. Enhanced support should also be considered for ramps and the raised floor areas immediately above them.
The raised floor load rating will vary depending on the design and use of the room. In most cases, a floor designed for a concentrated load imposed by stationary furniture and equipment of 1000 Lbs (454 kg) with a maximum deflection 0.080 inch (0.2 cm) from any point on panel top should be sufficient. Rooms or areas with high levels of motorized traffic or heavy rolling loads should consider a higher rated tile.
The raised floor system should be in compliance with the specifications laid out in the National Fire Protection Associations Document, NFPA 75: Protection of Electronic/Data Processing Equipment within the USA, or relevant National standards outside of the USA.
While the practice should be avoided when possible, it is sometimes necessary to locate data centers in seismically active zones. Seismic bracing for the raised floor system can normally be obtained from the floor manufacturer. As a general practice, heavier components should be installed lower on the racks to avoid top-heavy equipment.
No activity in the data center should be allowed to significantly degrade the environment. Because of the dynamic nature of a data center, it is often necessary to implement projects to address its changing needs or mission. This may encompass moving walls to expand or reduce the size of the computer space, replacing older floors or ceilings, or upgrading environmental support equipment, among other things. It is essential that these actions, meant to improve the stability and operation of the data center, are not allowed to degrade conditions and threaten uptime.
Precautions must be taken to control psychrometrics and air distribution, and to limit or contain contaminant production. Even though the actual activities are common, the environmental requirements of the computer room pose unique problems. Normal cutting, drilling or demolition is unacceptable without proper precautions.
Whether the data center is located in a new or existing structure, the building must be properly prepared to receive the hardware prior to its installation. Construction projects are expensive, and the construction of controlled data center areas is more expensive than most. There is always a great deal of pressure to meet deadlines and keep within costs, but it is extremely important that this is not achieved by cutting corners and settling for inferior workmanship.
A data center requires more precise control over temperature, relative humidity, airflow, and contaminants than does a typical office environment. If the specific needs of this environment are to be met, they must be addressed throughout the design and construction of the room. Prior to installation of the hardware, the room should be inspected to identify any remaining exposures, and all surfaces in the room must be appropriately decontaminated. The final punch-list items should include specific tasks designed to bring the computer room environment within specific parameters. The following actions should be performed in the general order listed.
All building materials should be chosen with an aim towards cleanliness and moisture retention. Materials should be chosen or treated to avoid shedding or deterioration that might be tolerable in more loosely controlled environments. Particular attention should be paid to areas in the direct airflow patterns of the room, and materials that require repeated movement or disturbance in the normal occupation of the room. Ceiling tiles should have a vinyl or foil face that will provide a moisture barrier, and will help protect the tiles from shedding as they are moved. All supply plenum surfaces should be constructed of appropriately treated materials, such as encapsulated concrete or galvanized or painted metals.
Ideally, materials in keeping with the design of a class 100,000 cleanroom should be considered appropriate.
Panels and other necessary items should be pre-cut and drilled outside the room to minimize the activity necessary within the room. This may add time and effort, but will help limit contaminant production within the room.
Not all activity can be performed outside the room, so it is also important that efforts are made to contain or arrest contaminants produced by activities performed within the controlled space. Plastic sheeting can be used to isolate work areas from other areas of the room. Portable filter systems can be rented or purchased to help arrest particulate in the air (it should be noted that these are normally only effective in localized areas). Vacuum units equipped with High Efficiency Particulate Air (HEPA) filtration should be used to address any contamination produced by drilling or sawing as soon as it is produced.
In addition, it is extremely important that the temperature, relative humidity and air distribution conditions are taken into account, and that these conditions are not significantly degraded. Doors to the data center must not be left open, it may be necessary to design a temporary personnel trap to limit exposure caused by increased traffic through the controlled spaces. Similar isolation may be necessary if changes to the room perimeter produce exposures. The job progression should be planned in such a manner so as to limit exposures. Care should be taken when removing floor tiles to ensure that the subfloor pressure levels remain adequate for proper air distribution. It is also important that any activity that involves the environmental support equipment be carried out without affecting the ability of the units to address the conditioning and humidification needs of the subject areas.
Proper implementation of construction and renovation projects in an on-line data center require additional time, planning and expense, but these precautions are essential if the uninterrupted operation of the data center is a priority. Ignoring these issues can lead to catastrophic failures, or long-term performance problems.
| Sun Microsystems Data Center Site Planning Guide | 805-5863-13 |
|
Copyright © 2002, Sun Microsystems, Inc. All rights reserved.