Black Box Explains...What to consider when choosing a rack.
There are several things you should consider when choosing a rack.
What kind of equipment will you be putting in it? If you need frequent access to all sides of... more/see it nowthe equipment, an open rack is more convenient than a cabinet. If your equipment needs ventilation, a rack poses no air circulation limitations. And don’t neglect aesthetics. Will customers or clients see your installation? A rack with cable management looks much neater.
Finally, consider security. Because a rack is open, you need to take steps to secure your equipment. Set up your rack in a locked room so prying fingers can’t access your network equipment.
Racks come in various sizes and installation styles. Some are freestanding; some are designed to be wallmounted. Some can be a combination of both styles, sitting on the floor but attaching to the wall for more stability.
Understanding rack measurements.
The main component of a rack is a set of vertical rails with mounting holes to which you attach your equipment or shelves.
The first measurement you need to know is the width between the two rails. It’s commonly given in inches, measured from one mounting hole to the corresponding hole on the opposing rail. The most common rail width is 19"; 23" rails and racks are also available. Most rackmount equipment is designed to fit 19" rails but can be adapted for wider racks.
The next important specification is the number of rack units, which is abbreviated as “U.” This is a measurement of the vertical space available on the rails. Cabinets and racks and rackmount equipment are all measured in rack units. One rack unit (1U) is equal to 1.75" of usable vertical space. So, for example, a device that’s 2U high takes up 3.5" of rack space. A rack that’s 20U high has 35" of usable space.
Because the widths are standard, the amount of vertical space is what determines how much equipment you can actually install. Remember this measurement of usable vertical space is smaller than the external height of the rack.
Getting power to your equipment.
Unless you want to have a tangle of extension cords, you’ll need to get one or more power strips for your rack. Consider which kind would be best for your installation. Rackmount power strips come in versions that mount either vertically or horizontally. Some have outlets that are spaced widely to accommodate transformer blocks—a useful feature if most of your equipment uses bulky power transformers.
Surge protection is another important issue. Some power strips have built-in surge protection; some don’t. With the money you have invested in rackmount equipment, you’ll certainly want to make sure it’s protected.
Any mission-critical equipment should also be connected to an uninterruptible power supply (UPS). A UPS prevents your equipment from crashing during a brief blackout or brownout and allows enough time to shut everything down properly in the event of an extended power outage. Choose a rackmount UPS for the most critical equipment or plug the whole rack into a standalone UPS.
Your equipment may look very tidy when it’s all mounted. But unless you’re very careful with your cables, you can create a tangle you’ll never be able to unravel.
Plotting your connections in advance helps you to decide the most efficient way to organize the cables. Knowing where the connections are tells you whether it’s better to run cables horizontally or vertically. Most network problems are in the cabling, so if you let your cables get away from you now, you’re sure to pay for it down the road.
There are many cable management accessories that can simplify your racks. collapse
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 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 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.
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.
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.
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.
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…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.
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.
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.
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
Black Box Explains...The fully accessorized rack.
After you choose your rack, consider how youll set it up and what accessories you might need.
Your rack may need to be secured. A typical rack has about a... more/see it now15"-deep base, providing some stability, but not enough to prevent the rack from tipping if heavy objects are mounted on it. To solve this problem, most rack bases can be bolted to the floor.
You also need to decide how to accommodate standalone equipment, which is not actually rackmounted or bolted to the rack. You can place small devices on a cantilevered shelf such as the RM001, however, you should place heavier items such as monitors on a center-weight shelf such as the RM377.
Small extras, such as Patch Panel Hinge Kits, can make your job easier. These hinges enable you to access the back of a patch panel simply by swinging it out from the rack. Theyre particularly useful for racks in hard-to-reach areas.
If you need to mount both 19" and 23" equipment in the same rack, use a 23" rack with 23"-to-19" Rackmount Adapters to fit the 19" devices.
For a neater appearance, you can cover unused spaces in a rack with Filler Panels.
Cable management is also an important consideration. Our Horizontal and Vertical Cable Managers help you to route cables along the sides of racks, between racks, and to the rackmounted equipment. collapse
Find the right screw length for your cabinet or rack.
Types of Screws
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.
Mounting flat-screen displays.
Traditionally, computer monitors, TVs, or other video displays have simply been placed on a shelf or desktop. However, today’s flat screens are less stable than older vacuum-tube displays and should... more/see it nowbe secured to prevent tipping. Fortunately, most new displays meet the VESA standard, meaning they have a hole pattern on the back that fits any VESA standard mounting device such as a wall mount, desktop mount, or ceiling mount. This enables you to secure the display to prevent damage from accidental jolts and bumps. Additionally, a mounted display is less likely to be the object of theft. collapse
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...Choosing a cabinet.
Understanding cabinet and rack measurements.
The main component of a cabinet is a set of vertical rails with mounting holes to which you attach your equipment or shelves. When you consider... more/see it nowthe width or height of a cabinet, clarify whether the dimensions are inside or outside.
The first measurement you need to know is the width of the rails. The most common size is 19 inches with hole-to-hole centers measuring 18.3 inches. There are also 23-inch and 24-inch cabinets and racks. Most rackmount equipment is made to fit 19-inch rails but can be adapted for wider rails.
After width, the most important specification is the number of rack units, abbreviated as “U.” It’s a measurement of space available to mount equipment. Because cabinet width is standard, the amount of space is what determines how much equipment you can actually install. Remember, this is an internal measurement of usable space and is smaller than an external measure of the cabinet or rack.
One rack unit (1U) is 1.75 inches of usable space and is usually, but not always, measured vertically. So, for example, a rackmount device that’s 2U high takes up 3.5 inches of rack space. A rack that’s 20U high has 35 inches of usable space.
Choosing the right cabinet.
Here’s a quick checklist of features to keep in mind before you choose a cabinet for servers or other network devices:
• High-volume airflow.
• Adjustable rails.
• Rails with M6 square holes.
• Moisture and dust resistance.
• Air filters.
• Front and/or rear accessibility.
• Locking doors.
• Left- or right-hinging doors.
• Power strips and cable organizers.
• Interior lighting.
• Availability of optional shelves, fans, and casters.
• Cable management rails, space, and knockouts.
• Extra depth to accommodate newer, deeper servers.
Don’t forget to accessorize.
Even if your cabinet is in a climate-controlled room, you may need to add a fan panel to help keep your equipment from overheating. It’s especially important to have ventilation in an enclosed cabinet.
Rackmount power strips mount either vertically or horizontally. Some have widely spaced outlets to accommodate transformer blocks. Some power strips include surge protection.
Mission-critical equipment should be connected to an uninterruptible power supply (UPS). A UPS keeps your equipment from crashing during a brief blackout or brownout and provides you with enough time to shut down everything properly in a more extended power outage.
For accessories that make cabling easier, just take a look at our many cable management products. We have cable management guides, rackmount raceways, horizontal and vertical organizers, cable managers, cable hangers, and much more. collapse