Power Management in Data Centers

Akey element of every data center's physical infrastructure is power, which
needs to be provided continuously to the equipment to ensure uninterrupted
services. Unfortunately, this is easier said than done due to many reasons. One
of them is the dynamic nature of data centers today.

Continuously, there's more equipment being added in data centers, which
requires the requisite power to scale up accordingly. So obviously, if you've
deployed a large, monolithic power management solution which can't be scaled
with the requirement, then you're in for trouble. What's required is a modular
power distribution and backup system, which can scale up with the

requirements.

Modular power units however, are not sufficient to cope up with the other key
trends taking shape in data centers. For instance, power density per rack is
also increasing in data centers thanks to the use of blade servers. Besides
raising the power requirements, denser racks also lead to greater heat
dissipation, thereby stretching the cooling system. The cooling system in turn
also requires better power management to continuously do its work. So once
again, it indirectly boils down to efficient power management and provisioning.

Another key trend that's related to data centers is IT infrastructure
consolidation. Increasingly, organizations are preferring a centralized IT
infrastructure over a distributed one. This improves the manageability, reduces
costs, and improves uptime of the IT infrastructure. At the same time however,
it requires better power management, because you're in a way putting all your
eggs in one basket. Power failure could have a drastic impact on your
organization's business.

All these trends have nearly doubled the energy consumption of data centers
over the past few years. In fact, as a thumb rule, half of the total energy
consumed in a data center is by the IT equipment alone. Unlike other equipment,
IT equipment requires cleaner power and better monitoring becaue it's more prone
to failure. So a combination of these factors is forcing IT departments globally
to monitor data center power consumption and find ways of increasing energy
efficiency.

In this article, we'll not talk about the backup solutions like UPSes that
can be used in data centers for cleaner power and backup. Enough has been
written about them by us as well as other media in the past. It would suffice to
say that you need a scalable UPS system, which can easily grow with your IT
requirements. So in this article, we'll focus on other aspects of power
monitoring and management, which starts from choosing the right IT equipment
itself, and then moves towards implementing solutions that can monitor and
manage the power distribution to them. So let's start with the equipment.

Choice of IT equipment

Most IT vendors today are harping about providing energy efficient hardware,
whether it's servers, storage, networking, or security. So before you can work
out a proper power management strategy for your data center, you need to study
the power consumption patterns of your existing equipment. Work out a strategy
to gradually phase out all energy efficient equipment and replace with energy
efficient ones. For instance, multi-core processors have caused a revolutoin in
the server space, by adding more compute capability within the same form factor.
You no longer need to invest in a bigger server box if you want more power. So
if you haven't already, you need to work out a strategy for replacing existing
servers in your data center with multi-core ones. Next, work out similar
strategies for other equipment, e.g. moving to Network Attached or centralized
storage over direct storage, to get better power consumption per Terabyte.

Using power saving technologies comes next. Server virtualization fits the
bill just fine, as it allows you to improve the utilization of your existing
servers, thereby reducing the need to purchase more boxes.

Once you've optimized the power consumption of the equipment in your data
center, you're ready to monitor its power usage.

Using power management software

With so much IT equipment, it becomes essential to monitor the power being
provided to them. Here you could go for direct or network attached power
monitoring solutions. It would keep track of peak and idle load on servers. When
the server is not in use, it could reduce the power supplied to it and vice
versa.

Moreover, today, you can get software that let's an administrator set
different power mgmt policies. You can also use software to keep track of energy
being utilized by different equipment and plan a solution to minimize
consumption.

Remote power management

Administrators can implement different hardware solutions to remotely manage the
power of equipment in the data center. Servers can be remotely switched on/off
or restarted. These solutions also provide you with the choice to restrict power
to any device.

Smart load shedding

Certain power management hardware equipment have embedded smart load shedding
features. Using this feature, non-essential equipment can be turned off when not
in use. Such a feature is quite useful in situations when mains supply is not
available. Turning off non-essential equipment would then improve the back-up
time of a UPS.

Three-phase power

Implementing 3-phase 208 V power supply helps consolidate power needs and it is
also simpler to implement and maintain as it uses fewer circuits as compared to
single phase power supply. This results in overall reduction of power
distribution units required to power the equipment and increase the available
amperage for each server rack.

DC power distribution systems

Such a system helps reduce power consumption as conversion from AC to DC occurs
only once at the main input to the building. The DC is fed directly to the
servers and it also keeps the battery charged.

DC-powered servers don't have power supplies built-in but these are
provisioned for elsewhere in the infrastructure. Using DC supply does away with
the need for extra conversion. But this technology is suitable only for large
data centers and there are not too many experienced people out there to handle
such systems.

Designing an efficient system

The common design problems that lead to reduction in efficiency are:

1. Power distribution units and transformers operating well below their full
load capacities.

2. Air conditioners for heating and cooling being used at the same place.

3. Tampering with the throttle valves of cooling pumps considerably reduces
their efficiency.

The solution to these problems is to create a well-structured/tested design
that places each of the equipment in the right order.

Employing effective cooling solutions

Cooling systems consume a considerable amount of the total energy consumed.
Therefore effective cooling solutions should be used so that there's no wastage
of power. Row oriented cooling has higher efficiency for high density. Shorter
air paths require less fan power. An effective floor layout plays an important
role in increasing the efficiency of cooling solutions.