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Black Box Explains…How to keep cabinets cool.

Networking equipment—especially servers—generates a lot of heat in a relatively small area. Today’s servers are smaller and have faster CPUs than ever. Because most of the power used by these... more/see it nowdevices is dissipated into the air as heat, they can really strain the cooling capacity of your data center. The components housed in a medium-sized data center can easily generate enough heat to heat a house in the dead of winter!

So cool you must, because when network components become hot, they're prone to failure and a shortened lifespan.

Damage caused by heat is not always immediately evident as a catastrophic meltdown—signs of heat damage include node crashes and hardware failures that can happen over a period of weeks or even months, leading to chronic downtime.

Computer rooms generally have special equipment such as high-capacity air conditioning and raised-floor cooling systems to meet their high cooling requirements. However, it's also important to ensure that individual cabinets used for network equipment provide adequate ventilation. Even if your data center is cool, the inside of a cabinet may overheat if air distribution is inadequate. Just cranking up the air conditioning is not the solution.

The temperature inside a cabinet is affected by many variables, including door perforations, cabinet size, and the types of components housed within the cabinet.

The most direct way to cool network equipment is to ensure adequate airflow. The goal is to ensure that every server, every router, every switch has the necessary amount of air no matter how high or low it is in the cabinet.

It takes a certain volume of air to cool a device to within its ideal temperature range. Equipment manufacturers provide very little guidance about how to do this; however, there are some very basic methods you can use to maximize the ventilation within your cabinets.

Open it up.
Most major server manufacturers recommend that the front and back cabinet doors have at least 63% open area for airflow. You can achieve this by either removing cabinet doors altogether or by buying cabinets that have perforated doors.

Because most servers, as well as other network devices, are equipped with internal fans, open or perforated doors may be the only ventilation you need as long as your data center has enough air conditioning to dissipate the heat load.

You may also want to choose cabinets with side panels to keep the air within each cabinet from mixing with hot air from an adjacent cabinet.

Equipment placement.
Don't overload the cabinet by trying to fit in too many servers—75% to 80% of capacity is about right. Leave at least 1U of space between rows of servers for front-to-back ventilation. Maintain at least a 1.5" clearance between equipment and the front and back of the cabinet. And finally, ensure all unused rack space is closed off with blank panels to prevent recirculation of warm air.

Fans and fan placement.
You can increase ventilation even more by installing fans to actively circulate air through cabinets. The most common cabinet fans are top-mounted fan panels that pull air from the bottom of the cabinet or through the doors. For spot cooling, use a fan or fan panel that mounts inside the cabinet.

For very tightly-packed cabinets, choose an enclosure blower—a specialized high-speed fan that mounts in the bottom of the cabinet to pull a column of cool air from the floor across the front of your servers or other equipment. An enclosure blower requires a solid or partially vented front door with adequate space—usually at least 4 inches—between the front of your equipment and the cabinet door for air movement.

When using fans to cool a cabinet, keep in mind that cooling the outside of a component doesn't necessarily cool its inside. The idea is to be sure that the air circulates where your equipment's air intake is. Also, beware of installing fans within the cabinets that work against the small fans in your equipment and overwhelm them.

Temperature monitoring.
To ensure that your components are operating within their approved temperature range, it’s important to monitor conditions within your cabinets.

The most direct method to monitor cabinet temperature is to put a thermometer into your cabinet and check it regularly. This simple and inexpensive method can work well for for small installations, but it does have its drawbacks—a cabinet thermometer can’t tell you what the temperature inside individual components is, it can’t raise the alarm if the temperature goes out of range, and it must be checked manually.

Another simple and inexpensive addition to a cabinet is a thermostat that automatically turns on a fan when the cabinet's temperature exceeds a predetermined limit.

Many network devices come with SNMP or IP-addressable internal temperature sensors to tell you what the internal temperature of the component is. This is the preferred temperature monitoring method because these sensors are inside your components where the temperature really counts. Plus you can monitor them from your desktop—they’ll send you an alert if there’s a problem.

There are also cabinet temperature sensors that can alert you over your network. These sensors are often built into another device such as a PDA but only monitor cabinet temperature, not the temperature inside individual devices. However, these sensors can be a valuable addition to your cooling plan, especially for older devices that don't have internal sensors.

The future of cabinet cooling.
Very high-density data centers filled with blade servers present an extreme cooling challenge, causing some IT managers to resort to liquid-cooled cabinets. They’re still fairly new and tend to make IT managers nervous at the prospect of liquids near electronics, but their high efficiency makes it likely that these liquid-cooled systems will become more prevalent.

It’s easy, really.
Keeping your data and server cabinets cool doesn't have to be complicated. Just remember not to overcrowd the cabinets, be sure to provide adequate ventilation, and always monitor conditions within your cabinets. collapse


Black Box Explains...Thermocouples

A thermocouple is a device that measures temperature by using the fact that a junction between two different metals produces a varying voltage related to their temperature. Two common types... more/see it nowof thermocouple are Type J and Type K.

Type J thermocouples use iron paired with a nickel-copper alloy. Type J thermocouples may cover a temperature range of up to -40 to +1382° F (-40 to +750°C), and offer high sensitivity.

Type K, the most common type of thermocouple, uses nickel-chromium and nickel-aluminum alloys. Because Type K is an early specification, its characteristics vary widely; individual thermocouples may cover a range of up to -328 to +2462 °F (-200 to +1350 °C). collapse


Cold aisle containment.

Cold aisle containment (CAC) is a cooling method that increases cooling efficiency and reduces energy costs in data centers.

This cooling method relies on the fact that most network equipment... more/see it nowand servers are designed to cool themselves by drawing air in through the front and exhausting it out the rear. To implement cold aisle containment, rows of cabinets or racks are arranged facing each other to form aisles, and cool air is routed between the rows. Equipment takes the cool air in at the front of the cabinet and exhausts it out the back into the room.

To keep cool air from mixing with warm air, row ends are closed off with an air-flow barrier. This barrier can range from makeshift arrangements of plastic strips to doors made expressly for this purpose.

Because cold aisle containment concentrates cool air at the front of equipment where it’s most needed, it’s an exceptionally effective cooling method. Cold aisle containment significantly reduces energy costs, lowering power bills as well as reducing data centers’ carbon footprints. collapse


Black Box Explains...Fiber connectors.

• The ST® connector, which uses a bayonet locking system, is the most common connector.

• The SC connector features a molded body and a push- pull locking system.

• The FDDI... more/see it nowconnector comes with a 2.5-mm free-floating ferrule and a fixed shroud to minimize light loss.

• The MT-RJ connector, a small-form RJ-style connector, features a molded body and uses cleave-and-leave splicing.

• The LC connector, a small-form factor connector, features a ceramic ferrule and looks like a mini SC connector.

• The VF-45™connector is another small-form factor connector. It uses a unique “V-groove“ design.

• The FC connector is a threaded body connector. Secure it by screwing the connector body to the mating threads. Used in high-vibration environments.

• The MTO/MTP connector is a fiber connector that uses high-fiber-count ribbon cable. It’s used in high-density fiber applications.

• The MU connector resembles the larger SC connector. It uses a simple push-pull latching connection and is well suited for high-density applications.
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Black Box Explains…Cooling blade servers.

Blade servers are hot. Really hot. These slim, high-powered CPUs generate heat like nothing you’ve ever installed in your data center before—a rack of blade servers can generate more heat... more/see it nowthan an electric oven! And as temperatures rise, servers may fail, leading to downtime and even data loss.

Needless to say, blade servers present a cooling challenge. If you plan to install them, you need to make sure you can accommodate their cooling needs.

Computer rooms have special equipment such as raised-floor cooling systems to meet their high cooling requirements, but it’s also important to ensure that cabinets used to house blade servers provide adequate ventilation—even in a cool room, hot spots can develop inside cabinets if air distribution is inadequate.

If you’re planning to install blade servers or other high-density components in cabinets, look for a cabinet with fully perforated doors in the front and rear— the greater the amount of perforation, the more cool air can be delivered to the components.

Don’t overload the cabinet by trying to fit in too many servers—75% to 80% of capacity is about right. Leave at least 1U of space between rows of servers for front-to-back ventilation. And finally, ensure all unused rack space is closed off with blank panels to prevent recirculation of warm air back to the front of the cabinet.

If you need help calculating your system’s cooling needs, contact our FREE Tech Support.
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Black Box Explains...Cable management.

Corporate networks are complex systems of PCs, servers, printers, and the devices that connect them. Getting everything to work in harmony requires bundles of cables, and managing all those cables... more/see it nowfrom inside a telecommunications closet can be a daunting task. To connect cable bundles to rackmounted equipment (like patch panels, hubs, switches, or routers), you need to direct the bundles overhead, vertically, and horizontally.

A popular choice for overhead cable routing is a ladder rack. Ladder racks come in many varieties. They can run along a wall supported by brackets or they can be installed overhead and supported by a threaded rod. Ladder racks can support large cable bundles neatly and safely. Because bundles lie flat on a ladder rack, cables aren’t subjected to harsh bends. You can run ladder racks directly to the top of most standard telecommunications racks that conform to TIA/EIA standards.

Use vertical cable managers to route cable bundles along the sides of a rack. These “cable troughs” as they’re sometimes called can be single sided—or double sided to route cable bundles to the rear of equipment and to the ports on the front as well. Vertical cable managers usually come with some type of protection for the cable, such as grommeted holes to protect the cable jacket or a cover that may clip on or act as a door.

Horizontal cable managers are usually a series of rings that directs cables in an orderly fashion toward the ports of hubs, switches, and patch panels. collapse


Black Box Explains...Power over Ethernet (PoE).

What is PoE?
The seemingly universal network connection, twisted-pair Ethernet cable, has another role to play, providing electrical power to low-wattage electrical devices. Power over Ethernet (PoE) was ratified by the... more/see it nowInstitute of Electrical and Electronic Engineers (IEEE) in June 2000 as the 802.3af-2003 standard. It defines the specifications for low-level power delivery—roughly 13 watts at 48 VDC—over twisted-pair Ethernet cable to PoE-enabled devices such as IP telephones, wireless access points, Web cameras, and audio speakers.

Recently, the basic 802.3af standard was joined by the IEEE 802.3at PoE standard (also called PoE+ or PoE plus), ratified on September 11, 2009, which supplies up to 25 watts to larger, more power-hungry devices. 802.3at is backwards compatible with 802.3af.

How does PoE work?
The way it works is simple. Ethernet cable that meets CAT5 (or better) standards consists of four twisted pairs of cable, and PoE sends power over these pairs to PoE-enabled devices. In one method, two wire pairs are used to transmit data, and the remaining two pairs are used for power. In the other method, power and data are sent over the same pair.

When the same pair is used for both power and data, the power and data transmissions don’t interfere with each other. Because electricity and data function at opposite ends of the frequency spectrum, they can travel over the same cable. Electricity has a low frequency of 60 Hz or less, and data transmissions have frequencies that can range from 10 million to 100 million Hz.

Basic structure.
There are two types of devices involved in PoE configurations: Power Sourcing Equipment (PSE) and Powered Devices (PD).

PSEs, which include end-span and mid-span devices, provide power to PDs over the Ethernet cable. An end-span device is often a PoE-enabled network switch that’s designed to supply power directly to the cable from each port. The setup would look something like this:

End-span device → Ethernet with power

A mid-span device is inserted between a non-PoE device and the network, and it supplies power from that juncture. Here is a rough schematic of that setup:

Non-PoE switch → Ethernet without PoE → Mid-span device → Ethernet with power

Power injectors, a third type of PSE, supply power to a specific point on the network while the other network segments remain without power.

PDs are pieces of equipment like surveillance cameras, sensors, wireless access points, and any other devices that operate on PoE.

PoE applications and benefits.

  • Use one set of twisted-pair wires for both data and low-wattage appliances.
  • In addition to the applications noted above, PoE also works well for video surveillance, building management, retail video kiosks, smart signs, vending machines, and retail point-of-information systems.
  • Save money by eliminating the need to run electrical wiring.
  • Easily move an appliance with minimal disruption.
  • If your LAN is protected from power failure by a UPS, the PoE devices connected to your LAN are also protected from power failure.

  • Converters and Scalers Selector
    PoE Standards PoE
    IEEE 802.3 af
    PoE IEEE 802.3 at
    Power available at powered device 12.95 W 25.5
    Maximum power delivered 15.40 W 34.20
    Voltage range at powred source 44.0-57.0 V 50.0-57.0 V
    Voltage range at powred device 37.0-57.0 42.5-57.0 V
    Maximum current 350 mA 600 mA
    Maximum cable resistance 20 ohms 12.5 ohms
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    Screw Dimensions

    Find the right screw length for your cabinet or rack.

    Types of Screws

    Screw Dimensions

    There are two basic kinds of screws used for cabinets and racks—panhead screws and countersunk screws—and... more/see it nowthey’re measured in two different ways. Because the standard way to measure is from the tip of the business end of the screw to where the screw rests on the material it’s fastened to, a panhead screw is measured to the bottom of its head, whereas a countersunk screw is measured to the top of its head.
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    Black Box Explains...Cabinet accessories.

    Once you’ve chosen your cabinet, whether it be a customized Elite or an energy-saving ClimateCab, it’s time to add accessories for even more function.

    Cabinets have two sets of rails,... more/see it nowfront and back, where you can mount shelves, trays, cable managers, and power strips.

    Shelves
    Shelves are an easy solution for storing things that aren’t rackmountable. The shelves attach to the rails; servers or other equipment sits on the shelves. Make sure the shelf has the weight capacity you need—some can hold hundreds of pounds. For easy access to components in your cabinet, choose a sliding shelf. There are also vented shelves that improve air circulation within the cabinet.

    Although most shelves fit 19" rails, there are shelves that go on the less-common 23" rails. There are also brackets that can adapt many devices intended for 19" mounting to 23" rails.

    Keyboard trays
    Keyboard trays are space-saving solutions that also keep your data center organized. They slide neatly into your cabinet or rack—and out of your way—when not in use. And they usually fit into only 1U of rack space.

    KVM trays
    Further reduce clutter in your server room by using KVM trays that are 1- or 2U high mounted in your cabinet. Special features of Black Box® KVM trays include rock-solid construction, LEDs on the front panel for easy location in a darkened data center, and integrated KVM switching.

    Front-panel controls enable you to use the buttons on a monitor bezel without pulling out the keyboard. Some trays have USB ports for access.

    Cable managers
    Cabinets usually have built-in troughs for cable routing, knockouts for cable pass-throughs, and tie-off points for cable management. You can also add horizontal or vertical cable managers to the cabinet’s rails to manage and route cables more efficiently. Cable managers control bend radius to protect cables from hidden crushes, kinks, and snags, and reduce maintenance time by keeping your cabinet neat and organized. Plus, properly managed cables help to improve airflow.

    SpaceGAIN
    If you’ve got no room to spare in your cabinet, think SpaceGAIN. You might not think of a patch panel as an “accessory,” but SpaceGAIN angled-port and angled patch panels are not your average panels. They free up valuable space and eliminate the need for horizontal cable managers. You save time and money by routing cables directly into ports. And SpaceGAIN high-density feed-through patch panels enable you to fit 48 ports into only 1U of rack space, with no punchdowns needed.

    To save even more space, use SpaceGAIN 90° Right-Angle CAT5e/CAT6 cables. Their up, down, left, or right angles save up to 4" of space in crowded cabinets.

    PDUs and UPSs
    Control the distribution of power in your cabinet with a power distribution unit (PDU). A PDU can be basic or “intelligent,” with surge protection, remote management, or power and environmental monitoring. Integrate a PDU directly into an uninterruptible power supply (UPS) for extra reliability.

    Fans and blowers
    Ventilation in your cabinets is critical for keeping vital equipment cool.

    An enclosure blower draws cool air from a raised floor at the bottom of the cabinet and delivers it right across the front of servers or other network components. It fits on standard 19" rails and uses only 2U of mounting space. This high level of ventilation lowers the temperature of cabinet hot spots by up to 15° F. Lowering temperatures protects your electronics against failure caused by overheating, which may enable you to install more equipment.

    Fan panels or fan trays direct maximum airflow with very little noise to heat-sensitive rackmounted equipment. Position them in your cabinet wherever you need them the most.

    Most network devices take in air through their front panels and expel it out the back. Filler panels in unused rack spaces help keep cool air in the front of the cabinet where it can be used by the equipment.

    Security
    Most cabinets come with a lock and key, but more advanced options are available to provide a higher level of security. Keyless options include combination locks and biometric locks that read fingerprints. collapse


    Black Box Explains...10-32, 12-24, and M6 rails.

    The rails on cabinets and racks typically come with one of three mounting options: 10-32, 12-24, or M6.

    The 10-32 and 12-24 options are round holes found on drilled and tapped... more/see it nowrails. You’ll find 10-32 openings on cabinets, while 12-24 holes are more commonly found on relay racks and frames. However, exceptions do exist. It’s very important to find out which type of mounting option your equipment requires before you order a cabinet or rack.

    M6 holes are square, rather than round. M6 rails were developed to hold rackmount equipment, and you will find them on most server cabinets.

    What makes M6 rails so popular on server cabinets? They’re adaptable. With just one cage nut, you can change a square hole into a round one. That gives you much more versatility in your equipment and mounting choices.

    If you have a wide array of equipment, such as rackmount servers, hubs, routers, and patch panels, your best bet is a cabinet with M6 rails. It will accommodate the rackmount servers, and the other equipment can be mounted on those same rails using cage nuts.

    If you’re unsure what type of cabinet, rack, or frame is best for your application, contact the experts at Black Box Tech Support. They’ll be glad to help you find the right enclosure for your equipment. collapse

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