Why do commercial data centers "intelligent" PDU

    Historically, corporate data centers were the first to emerge - that is how 10–15 years ago modernized computing centers of large corporations began to be called, as well as “grown up” server rooms for medium-sized enterprises. Corporate data centers today are much higher than commercial ones in the number of racks placed in them. However, with the advent of customers the opportunity to place their IT resources on specialized IT platforms of third-party organizations - commercial data centers - their popularity is steadily growing.

    One of the main reasons for this is to increase the attractiveness of the outsourcing model. More and more customers are realizing the economic advantages of this model, which allows them to quickly and effectively solve IT problems without significant capital expenditures (CAPEX). In addition, the use of services of commercial data centers allows you to quickly scale your IT assets - and, how to expand them, and, if necessary, minimize. This is the optimal model, for example, for solving problems of supporting seasonal surges in demand for IT services.

    The benefits of commercial data centers do not end there. An important economic advantage is that such facilities allow you to pay only really used resources. In addition, on the basis of commercial data centers, it is often more efficient to solve information security tasks, for example, related to repelling DDoS attacks. Today, more and more commercial data centers offer not only high resiliency, but also the possibility of implementing disaster recovery schemes, with operational load transfer to other sites. We should not forget that IT outsourcing can significantly reduce the need for highly paid specialists, and not only in IT, but also in engineering systems. Companies get the opportunity to focus on their core business by transferring IT support solutions to commercial data centers.

    When density grows

    Over the past few years, the overall power density (kW per rack) in data centers — both corporate and commercial — has increased significantly. Ten years ago, a typical server cabinet consumed 1-2 kW of electricity, and the PDU units installed in it were ordinary extension cords, differing from household appliances except by a large number of power outlets. Today, server cabinets require much more power from a PDU. The typical level is 4-5 kW, but quite a few cabinets are filled with equipment that consumes 5-9 kW. In operation there are cabinets for 10-25 kW and even more power.

    The AFCOM Institute identifies four power levels per rack:

    • low - up to 4 kW;
    • medium - 5-8 kW;
    • high - 9-15 kW;
    • extreme - 16 kW and above.

    This classification was proposed in 2014, and already today the “extreme” level for many companies looks quite working. According to the Uptime Institute, 41% of data centers already use racks with a capacity of over 20 kW.

    Increasing the power of IT equipment located in racks increases the requirements for monitoring the level of energy consumed. The higher the power, the more critical IT services “lives” in each rack, and the possible excess of the power level is fraught with a lot of negative consequences: from overheating to banal shutdown of the machine. And the growing popularity of commercial data centers leads to the fact that such monitoring should be carried out not only locally, but also remotely, through a convenient interface on any device convenient at the moment for the customer.


    PDUs with local electricity metering capabilities appeared on the market more than 20 years ago. However, these products are not widely used. The challenges of more accurate metering of the electricity consumed by IT equipment have led to the emergence of a new generation of PDUs with more extensive functions, including remote monitoring. These devices are called smart (smart), or "intelligent" PDU. In recent years, the popularity of such devices has increased dramatically, including due to the above-mentioned requirements for monitoring the consumption of IT equipment placed in commercial data centers.

    Commercial data centers that specialize in colocation services charge their services, as a rule, based on two parameters: area and electrical energy. At the same time, three main energy metering schemes are practiced:

    1. In the first case, the cost of renting a rack depends on the maximum allowable power per rack, while real energy consumption is not taken into account. In this case, customers pay a fixed price regardless of how much the rack-mounted equipment actually consumes. The downside to this option for customers is that when the equipment consumes little electricity, they have to overpay.
    2. The second option - payment for actually consumed electricity. In this case, “intelligent” PDUs are used, which allow consumption to be taken into account.
    3. 3 In some cases, the combined scheme is practiced, when the tariff takes into account both the maximum rack power and the actual consumption. In this case, the fixed cost component, which is based on the maximum allowable power, will be less than in the first embodiment. But this amount will be added to the one that is calculated on the basis of consumed electricity.

    Since, in practice, IT equipment consumes, as a rule, substantially less than the specified nominal value, it is often more beneficial for the customer to use tariffs that take into account the actual load. So, smart smart PDUs are needed.

    EXpert PDU Solutions

    An example of smart PDUs are eXpert PDU products . Founded in 2009, PDU eXpert is based in Wellington (United Kingdom) and is one of the leading European manufacturers of power distribution, control, monitoring and energy management equipment for data processing centers.

    In the PDU Expert product portfolio, “intelligent” PDUs are available in four versions:

    • Models with the N1 index provide total control of the power passing through the entire PDU, including the total current (A), input and output voltage (V), and electricity consumption (kWh) with all devices connected to the PDU;
    • N2 models differ from N1 models in that they allow monitoring at the level of each individual outlet. They provide an opportunity to obtain data on the power consumption of individual devices connected to the PDU;
    • N3 devices have all the same functions as the N1 models, but additionally allow you to remotely turn on and off individual outlets;
    • The most functional models N4 provide the ability to monitor individual outlets (like N2), and their remote on / off (like N3).

    In addition to the set of functions required by modern PDU devices, eXpert PDU products allow to solve a number of other important tasks, in particular:

    • Online load switching between the main (primary) and backup (backup) power sources. Such switching is carried out in less than 8 ms, which means maintaining uninterrupted supply of electricity to the load. The automatic transfer reserve feature is endowed with products with the ATS index - Automatic Transfer Switch;
    • Monitoring the working environment. This functionality is realized due to the possibility of connecting to the PDU up to eight different sensors: temperature / humidity, smoke, infrared radiation, door opening, air flow, water ingress.


    The need of data centers for “intelligent” PDUs is caused not only by economic issues, but also by tasks related to ensuring a high level of reliability. If racks use PDUs without a power monitoring function, of course, you can manually measure your consumption with a multimeter. But this procedure requires quite a lot of time, and even worse, it significantly increases the risk of possible incidents due to the “human factor”, since the process requires a certain intrusion into the infrastructure (opening the cabinet door, connecting a measuring device, etc.). Moreover, since such measurements can only be carried out from time to time, they do not allow to detect consumption peaks, as well as to calculate the total power consumed by IT equipment over a certain period.

    As each new generation of IT equipment increases power requirements, the use of conventional (non-intelligent) PDUs increases the risks more and more. Without accurate data on power consumption, the IT administrator will not know if you can still install servers in this rack, and if so, how many. Upgrading servers or even updating software can change its power consumption, and the lack of operational data is fraught with exceeding the permissible load on the rack with the already mentioned consequences (overheating, shutdown of the machine, etc.). As for adding new servers to the rack without having information about current energy consumption, this process will resemble Russian roulette and may lead to the most negative consequences.

    The need for continuous continuous monitoring of energy consumption is also associated with the changed structure of energy consumption of IT equipment. If 5-10 years ago, a typical server in sleep mode consumed about 50-60% of maximum power, then the current generation of servers is much more energy efficient: their consumption level in sleep mode is 20-25% of maximum power, or even less. As a result, electricity consumption has become much more uneven, with a large number of peaks and dips. The episodic consumption measurement by manual method does not allow to detect all the peak values.


    Modern data centers often use the PUE metric that our previous article was about to measure performance . However, we must understand that the value of PUE characterizes only the efficiency of the engineering infrastructure of the data center. An important task is to evaluate the performance of the computing environment itself, servers and data storage systems. To help solve this problem will help modern PDU units with the ability to measure the energy consumption of individual pieces of equipment.

    The availability of data on energy consumption will allow you to assess how it changes with changing operating environment, software updates or server hardware components. Having obtained such data, specialists can use them to correlate the performance indicators of IT equipment with energy consumption indicators. The resulting data can help assess how effective this or that upgrade is, as well as plan the development of the computing environment.

    In addition, the availability of information on power consumption on individual ports of the PDU allows you to identify the so-called zombie servers. The fact is that in the old data centers up to 10% of servers may no longer be used or unnecessary software may “spin” on them. Such servers not only occupy precious space in racks, but also consume electricity and cooling system resources. The elimination of such "zombies" will significantly improve the efficiency of the data center as a whole.

    The use of PDUs with the ability to individually disconnect power outlets, which are also present in the eXpert PDU product portfolio, will eliminate unauthorized activation of the equipment or its replacement without the proper approval of authorized employees. Unauthorized installation of equipment may result in excess of the allowed rack power, subsequent shutdown of the machine and termination of the provision of IT services.


    The efficiency of using “intelligent” PDUs is significantly enhanced by having centralized software capable of collecting and analyzing data from hundreds of such units. This software provides the necessary information through a user-friendly, intuitive interface that can be adapted to the needs of various categories of employees. An example of such software is the Symbiosis system, which was created by PDU eXpert together with a German partner company specializing in the design and development of engineering software products.

    An important feature of Symbiosis is the ability to work in a heterogeneous environment with equipment of different types and manufacturers. This software supports various eXpert PDUs — PDUs, ATSs, UPSs — as well as PDUs from other vendors, various air conditioners and sensors. Optimized universal SNMP drivers allow you to work with the equipment of various suppliers. At the same time, unlike most similar solutions that support only the basic function of GET, Symbiosis is able to perform a wide range of functions for measuring parameters and their control.

    Unlike the DCIM class control systems on the market, the Symbiosis system is free from many redundant functions and is more flexible and affordable. However, it is suitable for both small and medium server rooms, and can be scaled to service a complex from several data centers.

    Symbiosis allows users to set thresholds for each of the connected devices. After these restrictions are set, the system will automatically alert selected users, including via email notifications.

    Symbiosis software has been successfully used by many customers in different countries. For example, one of the world's largest telecom operators, Vodafone, acquired Symbiosis to control intelligent PDU devices from different manufacturers and a cooling system in the data center in Munich . Another example is the use of Symbiosis software in the Kesington Council data center for managing intelligent PDU KWX-N32A36x6-V1CB manufactured by PDU eXpert.

    Regardless of the size and level of energy consumption of the data center, the ability to track energy consumption and correlate it with the level of utilization of IT resources is a key function for managing the data processing center and strategic planning of its development. The addition of “intelligent” PDUs to modern management software, such as Symbiosis, allows, with a high degree of detail and convenience, not only to control energy consumption, but also to calculate this consumption by data center tenants, offering them the most attractive tariffs.

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