Evaluating Physical Attributes of the Data Center Site
Once you are aware of the risk factors facing a potential Data Center site, it is time to assess the physical features of the property by answering the following questions:
- Where is the site?
- Is it easy to reach?
- Does it have existing structures?
- If so, how suited are they to housing a server environment?
- Specifically, how well does the site support the key design strategies for constructing a productive Data Center?
Remember, you want your Data Center to be robust, modular, flexible, standardized, and to intuitively promote good practices by users.
There's an old saying in real estate that the three most important features about a property are location, location, location. The saying is equally true when evaluating a potential Data Center site, albeit for a different reason. Whereas a home buyer might care about location because of a residence's vicinity to a posh neighborhood, a Data Center designer cares because of how easy it is to reach the property and where it is in relation to the company's other server environments.
When examining a property, make note of how easy it is to enter and leave by answering questions such as the following:
- Is the site visible from a major roadway?
- Are their multiple routes to reach the property or just one?
- Could a hazardous materials spill or major traffic accident at a single intersection block access to the site?
Treat the property's accessibility the same as other Data Center infrastructure details—look for redundancy and stay away from single points of failure.
An ideal Data Center site can be reached easily and has several means of ingress and egress. A property with limited access affects the everyday delivery of equipment, because large trucks might be unable to reach the site. Limited access also influences the response time for emergency service vehicles to reach the site in a crisis.
Finally, determine if the property is located near large population centers. This influences how close your employees live and therefore how long it might take someone to reach the Data Center after hours if an emergency occurs.
Disaster Recovery Options
There are countless publications that thoroughly explain how and why to create a business continuation strategy for your company. While that topic isn't the focus of this book, it is a good idea to think about how a potential Data Center site fits in to your company's disaster recovery plan.
If your plan calls for transferring business functions from one Data Center to another, for example, note the distance between the property you are evaluating and your company's other server environments and answer the following questions:
- Are the locations close enough that network latency won't be a problem?
- Can employees travel from one site to another in a reasonable amount of time, even if major roadways are blocked or airline flights aren't operating normally?
- Are the locations far enough apart that they are both unlikely to be affected by a single disaster?
Likewise, if your company backs up information from the servers in your Data Center and stores the data tapes off-site, where are those facilities in relation to your potential Data Center property? The greater the distance between your Data Center and off-site storage facility, the longer it will take to retrieve and restore the data after a disaster.
Many sites evaluated for housing a Data Center are at least partially developed, whether they have little more than an empty building shell or a fully equipped office building with a pre-existing server environment. Whatever the building was previously used for, diagnose if the infrastructure that's already in place can accommodate your needs or at least be retrofitted to do so. Important infrastructure considerations are power systems, cooling systems, and structured cabling, as described in the sections that follow.
Assess the property's power systems, including its electrical infrastructure and standby systems by answering the following questions:
- How much power is readily available?
- Are there enough electrical circuits to support your Data Center?
- If not, is there enough physical capacity at the site to add more?
- Do power feeds come in to the building at more than one location?
- What alterations must be made to accommodate battery backup systems and standby generators?
- If the site already has standby systems, are they of sufficient capacity to support your Data Center?
- If the site doesn't have them, does it at least have the physical space and structural support for them to be installed?
Make note of how much redundancy is present in the electrical infrastructure and what single points of failure exist.
Data Centers require significantly more cooling infrastructure than the equivalent amount of office space. Therefore, measuring the cooling capacity of a potential Data Center site is important. To assess the cooling capacity of the site, determine the following:
- Can the building's existing cooling infrastructure provide adequate cooling for a Data Center?
- Is there adequate space and structural support on the site to support air chillers, condenser units, or cooling towers?
- How much modification must be done to the building's existing air ducting to reroute cooling?
Determine how much and what type of structured cabling already exists in and to the building. Determine if enough connections exist to support your Data Center and if cabling comes in to the building at more than one location.
Certain cabling media have distance limitations, so it is a good idea to measure how far cable runs must travel, both for the Data Center and throughout the building. Also make note of how much redundancy is present in the cabling infrastructure and what single points of failure exist.
Amenities and Obstacles
Aside from whatever power, cooling, and cabling infrastructure a building already possesses, there are several less obvious features that make a structure more or less amenable for housing a Data Center, including the following:
- Weight issues
- Loading dock placement
- Freight elevator specifications
- Miscellaneous problem areas
- Distribution of key systems
Some of these elements can make a site completely unsuitable to housing a Data Center, while others are merely matters of convenience. The sections that follow examine these elements in greater detail.
One of the most basic features to examine about an existing structure is its physical dimensions. Some of the questions you need to answer about the site's dimensions are as follows:
- Is there enough contiguous floor space to house your Data Center?
- How tall are the doorways?
- How wide are the halls?
- What's the distance from floor to ceiling?
These dimensions all need to be sufficient to enable Data Center equipment to pass through easily.
The area for the Data Center itself normally requires a minimum of about 13 feet (4 meters) from floor to ceiling, and much more is preferable. The clearance is to accommodate the raised floor, the height of most server cabinets, the minimum buffer space between the cabinet and the room's drop ceiling that is typically required by local fire codes, and space above the drop ceiling where ducting is routed. Additional space above the drop ceiling allows for easier and more effective cooling of the server environment—more area means that a greater volume of cold air can be pumped in to the Data Center—and so is desirable.
An unobstructed pathway must also exist among the Data Center, its corresponding storage room, and the exterior of the building, for transporting equipment. All entrances, corridors, doorways, and other openings along this path must be at least 8 feet (2.4 meters) high and at least 4 feet (1.2 meters) wide. These measurements are chosen to enable your tallest server cabinets and widest pallets of supplies to be transported within the building and into the server environment easily. If you have Data Center-related items that are larger in size, look for larger building clearances accordingly. That brand-new disk library you purchase to perform data backups can't do you much good if it does not fit through the Data Center doors.
Once you've determined whether server cabinets and pallets of materials can be transported without difficulty through the building, you need to make sure that none of them damage or crash through the floor. Consider the structural capacity of the building and how much weight the floor is designed to support, especially in the Data Center area. Pay particular attention to this if you intend to place the server environment on an upper level—their weight-bearing capability is normally less than on the ground floor.
Servers, cabinets, networking devices, or backup storage units can sometimes be damaged during transport to your Data Center. When this does happen, it is often attributed to the equipment being shaken while rolled across uneven ground or dragged over the lip of an entrance and having the item thump forcefully to the ground under its own weight. Although you can't control what happens during shipment, you can safeguard how equipment is treated once it arrives at your site.
Having a loading dock in close proximity to your Data Center reduces the chance of equipment damage, so it is very helpful if a property you are evaluating has one. Equipment can be rolled a short distance across level ground, either directly into the server environment or an associated storage room, rather than having to be offloaded from an elevated truck bed and shuttled a longer distance.
As stated earlier in the chapter, a freight elevator is mandatory if your Data Center is located anywhere but on the ground floor. As with the doorways and corridors, the freight elevator must be at least 8 feet (2.4 meters) high and at least 4 feet (1.2 meters) wide so as to accommodate everything from tall server cabinets to wide pallets of equipment. The freight elevator must also have enough weight-bearing capability to carry a fully loaded server cabinet. Today's heavier systems can exceed 1500 pounds per server cabinet location, and it is reasonable to assume that that number will increase.
If your company site doesn't have a suitable freight elevator, you might be forced to take drastic measures to bring large equipment in and out. Figure 2-2 shows workers raising a backup tape library six stories above the ground with ropes and pulleys, for its installation into a Data Center in Bangalore, India.
Figure 2-2 Moving Equipment Without a Freight Elevator
The lack of a freight elevator in this building means that large equipment bound for the Data Center must be raised by hand.
Happily, the tape library was undamaged during transit. Ignoring for a moment the hazard that transporting a piece of equipment poses for the device itself, it is certainly potentially dangerous to those who participate. Look closely at Figure 2-2 and you can see that one of the workers is straddling the external stairwell railing as he helps pull on the rope to lift the equipment crate. When the time comes for the device to be removed from the Data Center, it will have to be lowered from the sixth floor in this same manner.
A key reason to have someone with Data Center design and operation experience help evaluate a building is to identify inobvious trouble spots. Determining whether a structure has adequate infrastructure or tangible facilities such as a loading dock or freight elevator is a straightforward exercise; however, some buildings might have problem areas—from a Data Center perspective—that are not as easily noticed.
Carefully examine all aspects of the building, large and small, to ensure that nothing can interfere with the operation of a server environment. Consider issues such as the following:
- Where are immovable building elements such as structural columns and stairwells?— These might restrict how much floor space is usable for a Data Center.
- Does the building have a kitchen or cafeteria?— This is a potential fire hazard, and if a site has multiple structures, kitchens or cafeterias should be located in a different building from the Data Center.
- Where are the building's water pipes?— Plumbing can leak and therefore shouldn't be routed above the server environment.
Distribution of Key Systems
As you examine the site's existing infrastructure, look closely at how the systems are configured. You ideally want important systems, such as power feeds and data cabling, to be spread out, each entering the building at more than one location. Such physical separation helps protect infrastructure systems—two cable runs following different paths are less likely to both be damaged by a single event than if they each follow the same path, for example. Standby power systems such as generators or backup batteries make the site more robust, and are even more beneficial if they are dispersed on a property rather than clustered together.