Power distribution is sometimes viewed as one of the last decisions to make at the end of the critical power path within your server room or datacentre. The fact is that this is also one of the most important and critical. The reason is that, after investing in LV switchboards, uninterruptible power supplies and standby power generators decisions must be made which govern not only the connection of your loads but also whether and how to monitor them.
Power distribution units vary in outlet configuration and size and their ability to meter, monitor and report on an array of critical power related information. Then right choice of PDU will impact on the overall reliability and scalability of your server room or data centre environment. Here is our checklist for planning a PDU installation:
With the answers to these questions it is then possible to select from one of three types of PDU which includes: basic, metered and smart or intelligent.
Also known as a power strip, the basic PDU is little more than a socket extension strip for mounting in a server cabinet. The PDU will have several power outlets and may include spike/electrical noise filtering and surge protection. Some basic PDUs can be upgraded with additional modules to turn them into more advanced PDUs with metering functions.
Basic PDUs offer no remote monitoring and are ideal for small computer rooms and server rooms with a limited number of installed servers and IT equipment.
The next level in sophistication is that of the metered PDU. Metered PDUs provide power related information that can be used to show consumption for analysis and in a colocation data centre, for billing. The typical power related information monitored includes load current, kVA, kW, kWh, power factor, AC supply voltage (from a UPS system or mains power supply) and its frequency.
A metered PDU usually displays this information on a built-in display panel or GUI (graphical user interface). It may also be possible to access the information via a built-in or optional plug-in remote IP/SNMP interface. The information available from a metered PDU can be collated to check for individual PDU power consumption, as well as overall load balancing for the server rack, and overall server room and datacentre.
Metered PDUs are recommended for larger server rooms and data centres and especially those with shared resources (including electricity) which require individually billing.
Intelligent or smart PDUs are the most advanced type of power distribution product with additional features to a basic and metered PDU. What makes this type of product ‘Smart’ is the extra functionality built-in. The PDUs include an IP/SNMP interface as standard and this may even be a hot-swap module to allow upgrades and swap-outs without the need for load downtime. Connection to a local IP network allows the PDU to continuous report on power consumption and provide power related metrics locally or via a web interface to a data centre infrastructure management (DCIM) platform.
The advantages of continuous power monitoring even down to individual socket levels allows for instantaneous alarm reporting if safety thresholds are exceeded. Electricity consumption down to individual sockets is typically +/- 1% in accuracy allowing for timely and precision billing. Load balancing is also more precise as is the loading on upstream UPS systems allowing for redistribution of the critical power as required.
Intelligent or smart PDUs also tend to offer a wide range of additional monitoring accessories to enable them to monitor environment factors: temperature, humidity, water ingress, smoke and security.
In addition to the more advanced communications features, intelligent PDUs also tend to include switched outlets. This is an important feature as it allows individual power outlets to be remotely controlled i.e. switched off or on to assist local reboots or the powering down of individual servers. This can help to reduce the workload of data centre technicians during peak periods and with sever utilization during off-peak load periods as servers can be activated or deactivated remotely.
Power distribution is as an important decision as any other within the critical power path of a server room or data centre. Selecting the right PDU arrangement will ensure that it is easier to manage power to servers and IT equipment within a rack and scale the equipment accordingly. In addition, overall space can be optimised, and cabling made simpler for ease of swap-out, upgrade and maintenance. The information provided by a metered or intelligent PDU also helps to assist with load balancing, billing and understanding the power usage profile of a server room or data centre during peak and off-peak periods. The analysed data can help to improve energy efficiency and issues with cooling such as hot-spots and other environment monitoring concerns.
The datacentre industry is under immense pressure to reduce its energy usage and achieve a smaller carbon footprint. One of the biggest users of non-compute energy are the cooling solutions used within hyperscale down to medium and small-sized datacentres.
Datacentres need to look at their energy consumption not from a cost point of view but from the impact the industry, is making on the planet’s natural resources. One way to reduce this consumption is to adopt the most energy efficient systems be they for critical power, cooling, server technologies or infrastructure support in terms LED lighting and security but in hand with this and perhaps more importantly, datacentres need to accurately monitor their energy usage.