Environmental Considerations


When a network and server farm is set up in the data center, environmental factors such as power, cooling, and potential disasters must be considered. If outsourcing, the vendor should be able to provide details on the physical setup of the facility.

Power

The utilization of an emergency or standby generator is essential when considering power outages that may affect a data center. Outages caused by the local utility that last no longer than 15 minutes will typically be supported by an uninterruptible power supply (UPS). However, a standby emergency generator is necessary to support longer outages.

Each component has a power rating, usually in watts, that it requires for continuous use. At best, inadequate power will strain the power supply of the component. At worst, it will cause production failure. If the facility has a UPS, it must have adequate capacity now as well as the ability to handle future growth plans. Another consideration is how long can the UPS keep the systems running in the event of a sustained power failure? Is there a generator backup? If so, how many gallons of fuel does it have, and how many hours of operation will that yield? During a power failure, it may be difficult to gracefully shut down all of the servers and equipment. Liebert, Tripp Lite, American Power Conversion (APC), and other vendors provide good data center solutions, including software and hardware components for power backup, generator switchover, and server shutdown.

Assessing Your Power Requirements

The first step in assessing the actual power requirements and the resulting UPS need is to estimate the load. This is done in slightly different ways for different equipment, but it comes down to estimating the operating voltage, the load (in watts), and a factor for how often the unit is in operation at this voltage and load—sometimes called a power factor. An example for a high-end server might be: operating voltage = 120 volts, load = 400 watts, and power factor = .75 (since it is in continuous operation at nearly peak utilization). This information should be readily available from the manufacturer either in printed documentation or from their web site. A company should collect and total this information for all of their equipment. Using this example, 15 servers would require 4500 watts (400 .75 15) plus a "fudge factor" in case multiple servers suddenly run at peak loads—5000 to 5200 watts would be wise.

Next, the site voltage should be determined. Data center facilities can often handle multiple voltages, but 230V/400V is common. An organization needs to consider how much room for growth they will need, and make sure there are adequate connections to support future equipment.

Note

Facilities at an LEC might also supply 48VDC.

Uninterruptible Power Supply

Organizations selecting an uninterruptible power supply (UPS) need to determine how long they need their equipment to remain functional after power fails. A UPS vendor will be able to provide you an estimate of run time after power failure based on the total number of watts for your equipment. UPS systems are usually rated in volt-amps. The conversion from watts to volt-amps is V A = W / 0.8. Using the earlier example, 5200 watts would require (5200 / .8) = 6500 volt-amps.

HVAC Units for Cooling and Humidity Control

We have been called in to many organizations to resolve unstable software and server problems, only to discover that the temperature where the servers were running was well over 90 degrees Fahrenheit. Servers and Telco equipment generate a great deal of heat, and will function inconsistently and often sustain permanent damage if their environment has significant temperature variations or remains consistently warm (typically, 66–70 degrees Fahrenheit is considered optimal, with temperature variations of no more than +/-5 degrees per day). The less the variation and the cooler the temperature (but not below 65 degrees), the longer the equipment will operate optimally. Cooling should not only be sufficient for normal operation, but should have adequate backup. The ideal situation is to have a redundant cooling system with sufficient power backup to support it.

The cooling system utilized must not add excess moisture to the environment. Industrial evaporators are available to avoid this potential problem. Many higher-end cooling systems have built-in moisture suppression. Detectors should be installed to provide an alert when moisture exceeds recommended levels. Keep in mind that a dry environment means that people working in the data center should drink adequate amounts of water, thus water fountains should be placed at convenient locations.

HVAC Evaluation

When evaluating HVAC units, the following factors should be considered:

  • The temperature and humidity tolerances of equipment

  • The amount of space to be cooled (in cubic feet)

  • The period of operation (evenings? weekends?)

  • Seasonal needs (are some months much hotter than others?)

  • Whether people will be working for prolonged periods in close proximity to the equipment

Fire Suppression

Data center certified fire suppression systems are extremely important in any operational facility. The systems use some type of mechanism to help extinguish fires without damaging hardware or facilities. Today's fire suppression systems must comply with environmental concerns regarding ozone depletion and human safety. This is an important consideration if the data center will be staffed and there is a potential for the fire suppression system to be activated while people are present.

Fire Suppression System Types

Many types of systems are available that comply with environmental requirements and use different agents to suppress fires. We recommend comparing the quality of the different types of fire suppression systems to determine which one best fits the data center setup. Table 5-1 lists the advantages and disadvantages of some of the different systems currently available.

Table 5-1: Comparison of Commercial Fire Suppression Systems

Type of System

Chemical Agent

Advantages

Disadvantages

Precharge sprinkler

Water

Provides the best suppression of all fires and protection for structures. No water sits above sensitive equipment.

Extra plumbing is required, including lines and routing of pipes to avoid the data center and sensitive equipment. Major water damage is likely when discharged.

Wet sprinkler

Water

Provides the best suppression of all fires and protection for structures.

Accidental discharge from human or environmental factors can set it off. Major water damage is likely when discharged.

FM-200

Heptaflouropropane

Doesn't displace oxygen, so it is safe when people are present.

High cost.

Inergen

Argon, nitrogen, and CO, (stands for 2 Inert gas and nitrogen)

Allows storage or flow over data center room. Inergen leaves enough oxygen for people to breathe.

High cost, large storage space.

Seismic and Other Environmental Activity

For data centers in California or other seismically active areas, adequate facility bracing is a must. Facilities should meet or exceed the earthquake regulations for the area. In addition, computer hardware racks and cabinets, and other equipment should have their own bracing and be able to pass inspection. Other geographical areas have different environmental concerns that should be planned for; for example, possible hurricanes in Florida, or major snow storm-based power outages in some northern states.

Physical Security

If most, or all, of an organization's computing infrastructure will be housed at a data center, it is imperative that physical access be restricted and monitored. Many outsourced hosting facilities have security guards, card-key access, motion sensors, and silent alarms. Despite tremendous amounts of time and money spent protecting a network with hardware and software security, data can still be at considerable risk if physical security is not considered. We discuss security in more detail in Chapter 8.




Citrix Metaframe Access Suite for Windows Server 2003(c) The Official Guide
Citrix Access Suite 4 for Windows Server 2003: The Official Guide, Third Edition
ISBN: 0072262893
EAN: 2147483647
Year: 2003
Pages: 158

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