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Why Are Redundant Power Supplies Important

When you have to maintain a network, power is important. Obviously, every device needs a source of power, but when you get into more complicated networks where downtime can be extremely expensive and infrastructure costs also run high, power becomes a central part of your planning and strategy.

You’ll think about where to run power lines, how much power is needed in each segment of the network, and a whole lot more. Among those concerns is redundancy. How do you keep your network online if a piece of equipment loses power? One answer is with a redundant power supply.

What Is a Redundant Power Supply?

A redundant power supply (PS) is an extra power supply for a single piece of equipment. Imagine a personal computer as an example. The power supply is typically housed in the computer case with the rest of the hardware. It regulates the flow of electricity so the finer components have a stable, safe stream of power.

A redundant power supply adds an additional PSU (power supply unit) to the build, typically in the same case. When there are two power supplies, each provides half of the electricity that the device needs in order to operate. If one of the PSUs fails, the other can instantly compensate and provide all needed power.

It’s worth noting that you can have as many redundant power supplies as you want. If a device has three PSUs, then each will typically provide a third of the power needed for the device, and so on.

Cisco has networking equipment that uses something called Dual Redundant Power Supplies. This is a redundant power supply for switches that is modular. That means you can change out the PSUs for the device at will, making it easier to customize redundancy and replace faulty power supplies.

Redundant Power Systems

Cisco also makes something known as the Redundant Power System (RPS). While a redundant power supply is typically housed in the same case as the rest of the hardware for a device, this power system is external. In fact, it can operate as a redundant power supply for multiple devices at the same time. It can even provide PoE to endpoint devices.

This system allows for more efficient redundancy, lowering overall equipment costs. But, it comes as a trade-off. If multiple devices are backed up by a single power supply, then that leads to a network with less overall redundancy and a higher chance of power failure and downtime.

What Are the Advantages of Redundancy?

Speaking of downtime, it’s the essential reason for redundant power supplies. Hardware can fail. Circuits can fail. There are multiple ways to lose power to a piece of equipment, and in a network, that leads to partial or even total downtime.

Downtime is expensive, so preventing it is often worth an investment, and that’s the principle of redundant power. It helps prevent common sources of downtime altogether, and in many cases, this redundancy pays for itself.

In fact, there are two specific applications of redundant power that are worth noting.

Hot Swapping

When you have a redundant power supply, you can often take advantage of hot swapping for repairs. Imagine that one PSU fails. The other kicks in and your device works without issue. Because the other PSU is handling the entire electrical load, you can hot-swap out the failedunit and replace it without taking the device offline.

Not all devices are built for hot swapping in this way, but it’s a common benefit.

Multiple Power Circuits

Perhaps even more compelling is the idea of utilizing different power circuits. Each power supply for a device has its own source plug. That means you can plug each power supply into a completely different circuit.

If a breaker trips and kills power to one unit, the other is on a different circuit and can function normally. This extends your redundancy beyond the device itself. You’re now operating on redundant power circuits.

Overall, redundancy is always important. While there are diminishing returns on the value of redundancy at a point, many professional networking devices come with redundant power supplies already. It’s simple to take advantage of this design philosophy, and you can often do so without changing your budget.

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