UPS Topologies
UPS Topologies - Offline
First, let's look at the least expensive topology, which is offline. These systems provide basic filtering and battery backup and they are typically used in desktop and non-critical applications.
UPS Topologies - Line-Interactive
The next UPS topology type is line-interactive, and includes the Liebert PSI. Line-interactive UPSs. They can be used in critical data applications and they carry a relatively low initial cost. This technology provides greater protection to IT equipment than offline UPSs.
UPS Topologies: Double-conversion, Online
Now, let's look at double-conversion online UPSs, such as the Liebert GXT and Liebert Nfinity. They offer the best protection for high-availability applications, such as converged voice and data. These UPSs are the most effective systems in terms of their ability to condition power. They use rectifiers and inverters to transform incoming AC power to DC and then back to AC to provide clean power without irregularities to the load.
Double-conversion, online UPSs have batteries that are continuously connected. This is important because if the incoming AC is interrupted the batteries continue to supply power with no delay. These systems provide fault-tolerant operation, because they have an automatic bypass that ensures continued power in the event of a component failure.
Network Critical Physical Infrastructure
There are several components that make up the NCPI.
- Power
- Cooling
- Racks and Physical Structure
- Cabling
- Physical security and fire protection
- Management and Services
The Network-Critical Physical Infrastructure (NCPI) is the foundation upon which IT and Telecommunications reside. It's the combination of all of these elements which allows IT to function.
Precision Cooling
The conventional legacy approach to data center cooling using room-oriented architecture has technical and practical limitations. The need of next generation data centers to adapt to changing requirements, to reliably support high and variable power density, and to reduce electrical power consumption and other operating costs have directly led to the development of row and rack-oriented cooling architectures. These two architectures are more successful at addressing these needs, particularly at operating densities of 3 kW per rack or greater. The legacy room-oriented approach has served the industry well, and remains an effective and practical alternative for lower density installations and those applications where IT technology changes are minimal.
Row and rack-oriented cooling architecture provides the flexibility, predictability, scalability, reduced electrical power consumption, reduced TCO, and optimum availability that next-generations data centers require. Users should expect that many new product offerings from suppliers will utilize these approaches.
It is expected that many data centers will utilize a mixture of the three cooling architectures. Rack-oriented cooling will find application in situations where extreme densities, high granularity of deployment, or unstructured layout are the key drivers. Room-oriented cooling will remain an effective approach for low density applications and applications where change is infrequent. For most users with newer high density server technologies, row-oriented cooling will provide the best balance of high predictability, high power density, and adaptability, at the best overall total cost of ownership.
Racks
Racks are the basic building blocks of the data center. Cutting edge rack technology streamlines cable management and provides the ability to vertically stack IT equipment reducing server sprawl and maximizes IT real estate. How these racks and enclosures are selected and configured affects a data center's availability and agility for years after the installation is completed.
Two standards for racks and enclosures:
- The 19 inch standard
- Earthquake standards
The Electronics Industries Association (EIA) established the EIA-310 standard to ensure physical compatibility between racks, enclosures, and rack mounted equipment. The intent of the standard is to ensure compatibility and flexibility within the Data Center. EIA-310 is used world-wide for 19-Inch Rack-Mounted equipment.
The use of sqare holes and cage nuts are most common, although some require threaded holes or non-threaded through holes. Square holes with cage nuts come in several thread sizes and types. If a cage nut's threads become damaged, fixing it is as easy as replacing the cage nut. Also, because the cage nut "floats" in its mount, the nut has some freedom to move which makes nut and bolt alignment easier.
Open Frames
Open frame racks rely on convection to dissipate heat. As the rack density increases, convection is limited in its ability to dissipate heat.
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Advantages
- Easy equipment acess
- easy assembly
Disadvantages
- No physical security or protection
- Exposed equipment
- They do not allow for optimized airflow
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Enclosures
There are several varieties of enclosure designs. Most enclosures include front and rear doors, side panels and a roof. Inside the enclosure, channels are created for forced air to move through the IT equipment providing enhanced cooling over open racks.
Depending on the manufacturer, other options may be available such as cable management, power distribution units, power protection, cooling, environmental management systems and other accessories.
Enclosure sizes
- 42U x 24" wide x 42" deep (common for servers)
- 42U x 29.5" wide x 42" deep (for servers & Networking with high density cables
- 47U x 24" wide x 42" deep (High ceilings)
- 47U x 29.5" wide x 42" deep.
Good front-to-back airflow is critical to effective cooling. Perforated front and rear doors provide maximum ventilation.
Blanking panels are important to cover empty rack spaces. The purpose of the blanking panels are to prevent heated exaust from being recirculated and entering IT equipment intakes. Additionally, standardizing on a 1U panel size offers the most flexibility and ease of installation especially if the panels snap-in.
Poor cable management often causes airflow obstructions. Wires form "rat's nests" making it difficult to identify power and data cables. Abandoned cables get intertwined with active cables and block airflow.
Frequently changing power and cooling demands require an adaptable and scalable rack solution. Racks may have to support different power requirements, multiple supply voltages or several outlet types. Rack systems need to provide tool-less Power Distribution Units (PDUs), and three phase power whips to support changeover capability for different voltages, power capabilities and outlets.
Changeing room layouts cause migration and mobility problems. Rack enclosures should provide field-reversible doors, quick-release hinge pins, quick-release side panels, and casters for mobility. Racks should also adapt to new overhead power and data cabling sytems.
Enviromental monitoring helps identify thermal gradients from the top to the bottom of the rack. It also helps detect hazards such as smoke and himidity extremes. Any large thermal gradient could lead to equipment damage or shutdown. Enviromental monitoring provides monitoring devices and a graphical user interface that allows remote monitoring, along with automatic email, pager or telephone nitification of changes in the rack level enviromnent.
Rack locks as well as automatic notification to report and manage rack level securituy breaches are import for rmission-critical environments.
Finally, racks should be arranged to form alternating hot and cold aisles. Optimally, cold aisles are four feet wide and hot aisles are three feet wide.
