10 Factors to consider when choosing a cabinet or rack

The sheer number and different types of cabinets and racks can make choosing the right one for your data center a daunting task. But, if you consider your requirements one at a time, you can zero in on the right cabinet or rack for your application.

A cabinet is an enclosure with four rails and a door (or doors) and side panels. A rack is an open, freestanding 2- or 4-post frame that doesn’t have doors or sides. The decision on whether to use a cabinet or rack depends on a number of factors.

1. Equipment data-center
Before you choose a cabinet or rack, you need to determine what equipment you’re planning to house. This list can include servers, switches, routers, and UPSs. Consider the weight of your equipment as well. The extra stability of a cabinet might be important if you’re installing large, heavy equipment like servers. An open rack is more convenient than a cabinet if you need frequent access to all sides of the equipment.

2. Environment
With the open design, racks are a good choice in areas where security isn’t a concern such as in locked data centers and closets. And racks typically cost less than cabinets.

Cabinets, on the other hand, protect equipment in open, dusty, and industrial environments. Aesthetics can be a factor too. Will customers or clients see your installation? A cabinet with a door looks much neater than an open rack. When you’re trying to create a professional image, everything counts.

3. Ventilation
If your equipment needs ventilation, a rack offers more air circulation than a cabinet. Even if your cabinet is in a climate-controlled room, the equipment in it can generate a lot of heat. The requirements for additional airflow increase as more servers are mounted in a cabinet. Options to improve airflow include doors, fans, and air conditioners.

4. Size
Width: The width between the rails in both cabinets and racks is 19 inches with hole-to-hole centers measuring 18.3 inches. But there are also cabinets and racks with 23-inch rails. Most rackmount equipment is made to fit 19-inch rails but can be adapted to fit wider rails.

Rack Units: One rack unit (RU or U) equals 1.75″ of vertical space on the rails. A device that’s 2U high takes up 3.5 inches of vertical rack space. Rack units are typically marked on the rails. The number of rack units determines how much equipment you can install.

Depth: Cabinets and four-post open racks come in different depths ranging anywhere from 24″ to 48″ to accommodate equipment of varying sizes, particularly extra-deep servers. The rails on some cabinets and 4-post open racks are also adjustable to different depths.

When you consider the width, height, and depth of a cabinet or rack, clarify whether they are inside or outside dimensions.

5. Weight
Cabinets and racks vary in terms of the amount of weight capacity. Some cabinets can hold 1,000 pounds or more. Carefully consider the weight of your equipment and decide where you want to mount it before choosing a cabinet or rack.

6. Rails
The vertical rails in cabinets and racks have holes for mounting equipment. Two post racks typically have threaded 12-24 or 10-32 tapped holes. 4-post racks and cabinets often have M6 square holes for mounting servers.

7. Moisture, dust, shock, vibration
When housing electronic components outside of a protected data center, look for a cabinet with a NEMA (National Manufacturers’ Association) rating. NEMA standards are designed for corrosion resistance, protection from rain, submersion, liquids, dust, falling objects, and other hazards. There are also NEBS-Telcordia standards for protection against seismic activity, shock, and vibration. Cabinets and racks can also be bolted to the floor for extra stability.

8. Power provisioning
There are multiple options for powering rackmounted equipment. Power strips mount can be mounted vertically or horizontally. Power Distribution Units (PDUs) and Power Managers have additional capabilities such as remote management and metering. Uninterruptible power supplies (UPSs) typically mount in the bottom of a cabinet or rack because of their weight.

9. Cable management
Most cabinets and racks have built-in cable management troughs and cable rings for routing cable. For more information on cable management, see 9 Ways to Improve Data Center Cable Management.

10. The extras
The type of shelving you choose depends on the equipment you plan to mount. There are multiple options: solid, vented, stationary, and pull-out shelves. And there are shelves built to hold specific pieces of equipment, such as servers or keyboards. Other extras include fans, waterfall brackets, and grounding bars.


Why you need a UPS

Every day, interruptions to electrical service in homes, businesses, and public sector organizations occur. The losses from these power outages can be extensive and of great consequence. For a business, the recovery time is significant and the costs are high. According to PricewaterhouseCoopers research, after a power outage disrupts IT systems:

  • More than 33% of companies take more than a day to recover.
  • 10% of companies take more than a week.
  • It can take up to 48 hours to reconfigure a network.
  • It can take days or weeks to re-enter lost data.
  • 90% of companies that experience a computer disaster and don’t have a survival plan go out of business within 18 months.

Power outages can cause substantial losses for the companies affected. According to the U.S. Department of Energy, when a power failure disrupts IT systems:

  • 33% of companies lose $20,000 – $500,000.
  • 20% lose $500,000 to $2 million.

Why a UPS?
A UPS protects IT equipment and other electrical loads from problems that plague our electrical supply, performing the following three basic functions:

  • Preventing hardware damage typically caused by surge and spikes. Many UPS models continually condition incoming power as well.
  • Preventing data loss and corruption. Without a UPS, devices that are subjected to a hard system shutdown can lose data completely or have it corrupted. In conjunction with Intelligent Power Manager, an Eaton UPS can facilitate a graceful system shutdown.
  • Providing availability for networks and other applications while preventing downtime. In some cases, they provide enough battery runtime to ride through brief outages; in other cases, they provide hours of runtime to ride through extended power outages. UPSs are also paired with generators to provide enough time for them to power up. Continue reading

Fighting the summer storms – Choosing a UPS or BPS

Summer is storm season and that means an increased risk of equipment damage and data loss from lightning strikes, power anomalies, power outages, etc. One good zap can sideline your company’s operations in an instant.

Most power problems are brownouts (low voltage) or blackouts (complete outages). Only an uninterruptible power supply (UPS) or a backup power supply (BPS) can protect your systems against conditions of too little power.

To prevent power disasters before they happen, more than 70% of servers are protected with a UPS or BPS. Network managers know that having a server down brings many operations to a halt. Although the loss of a single hub or router may not bring the entire corporation to a standstill, it can result in zero productivity for entire workgroups or remote offices.

A UPS or BPS keeps power flowing, giving you enough time to shut down safely during a power outage. It also regulates your power, smoothing out dangerous overvoltages and undervoltages, spikes, surges, and impulses that often go unnoticed.

The difference between a UPS and a BPS is that a UPS provides continuous power that stays up during a power outage whereas a BPS provides standby battery backup to which it switches during a power problem.

Eaton 5110 UPS, 700 VA/420 Watts UPS

With a UPS, your equipment is always running on battery power, which is continuously being recharged from your regular power lines. Because there is no switchover time with a UPS, it’s a particularly stable source of power. Continuous UPSs, although they can cost twice as much as a standby BPS, provide extremely stable power and are frequently used in server rooms and other critical network applications.

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Solar storms—threat or too much hype?

Lately, it seems that every week or so, there’s a news story about solar storms, explosions, and flares, which, as the news stories ominously tell us, can take down entire power grids, disable phones and satellite navigation, and generally wreak havoc with electronics. But yet we seem to continue getting power and everything continues to function. Are solar storms all just hype or is there really a threat?

The sun is now entering the most active part of its cycle, producing explosions that spin solar winds towards the Earth. These solar storms produce damaging bursts of radiation, radio, and magnetic emissions and are perfectly capable of taking down power grids and computer networks. There is a long history of solar storms causing damage. In 1859 a solar “super storm” caused auroras that lit up the skies as far south as the Caribbean and disabled telegraph systems. In 1972, a solar flare disabled telephone service in Illinois. In 1989, a solar disturbance brought down the power grid in Quebec.

The current solar storm cycle is expected to peak in 2013. If it produces another solar super storm like the one in 1859, the effects would be devastating. Not only are today’s sophisticated electronics are far more vulnerable than 19th-century telegraph systems, but we’re also far more dependent on those electronics. A massive solar storm could easily bring down power grids around the world, ground planes, and disable the Internet.

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Storm season = surge protection

It was a dark and stormy night.

A line of storms blew through the Black Box campus in Lawrence, Pennsylvania yesterday. The power flickered, the UPSs beeped, and we were reminded again that it’s that time of year. It’s time for summer power problems.

Summer with its electrical storms, downed trees, and cranked-up AC, always seems to bring out the worst in our power grid. We tend to suffer from fading power—the lights dim and the background hum of civilization drops a notch, then recovers a few moments later when the power gets back up to speed.


APC Smart-UPS® 5000VA, 208V Rackmount/Tower for 5U: Rackmount or tower protection for your high-powered servers, telecom equipment, and business cricital systems.

Less often, we get a power surge like the big one we had at my home recently. The surge killed a couple of small appliances, but our nice new flat-screen TV was okay because a surge strip bravely gave up its life to save it. Part of the surge strip actually melted and the house smelled like ozone and burnt plastic for a couple of days afterwards. This is exactly what a good surge protector is supposed to do—sacrifice itself to preserve the expensive stuff when the big jolt comes through. Wish I’d thought to put a surge protector on the microwave.

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