Ten things you didn’t know about rack PDUs

It’s easy to dismiss rack PDUs, also called enclosure power distribution units or ePDUs, as glorified socket strips that simply provide somewhere convenient to plug in the power leads of rack-mounted hardware. This is indeed part of their function, but the latest rack PDUs do much more, and can make a big contribution to the efficiency, economy and resilience of IT installations ranging from small data cupboards to the largest data centres. Let’s look at ten key benefits you may not have considered.

1. Enhance the reliability of your IT installation

Modern IT systems have a sophisticated power infrastructure designed to guard against unplanned downtime and data loss. But this doesn’t help if the plug on the power lead for a server is accidentally knocked out of its socket. To guard against this, some rack PDU suppliers have developed systems that use plug retainers, cable trays or special proprietary power leads. Unfortunately, retainers and cable trays take up valuable space in the enclosure and are often inconvenient to use, while the proprietary leads cost up to 50% more than their standard counterparts. Rack PDUs are, however, now available with a plug retention feature that takes up no extra space and works perfectly with standard power leads. These rack PDUs deliver maximum reliability without the drawbacks of older solutions.

2. Tell you where your energy is going

The latest rack PDUs can provide optional energy monitoring right down to socket level, if required, and the meters used to measure energy usage offer IEC ±1 per cent billing grade accuracy. This means users can quickly determine exactly where energy is being used; ensuring that rogue hardware that is consuming more energy than it should is quickly identified. Accurate metering also simplifies load balancing and reveals locations where there’s spare power capacity. Further, billing-grade metering means that the energy data provided by the rack PDU can be used to apportion costs between company departments in enterprise installations and between clients in data centres.

3. Help cut your cooling costs

The trend in modern IT systems is to use less cooling but this often means higher temperatures in the rack enclosure. Most modern hardware is designed with this in mind, but older rack PDU systems may not be able to cope and may make it necessary to provide additional cooling. New generation rack PDUs can work continuously at up to 60 ºC without derating, so they’re ready to play their part in reducing cooling costs.

4. Simplify maintenance and upgrades

Older rack PDUs often got in the way of access to other rack-mounted hardware making it difficult, for example, to hot-swap server components in order to maintain operational continuity or to install hardware upgrades. The latest rack PDUs have a low-profile design, which allows full access to all rack-mounted equipment. In addition, they themselves incorporate hot-swappable components, such as meter boards, which can be fitted or exchanged without interrupting the supply to the loads. As a further benefit, the best rack PDUs are colour coded so that maintenance technicians can see at a glance which circuit breaker controls which socket.

5. Put you in control of your power

With switched rack PDUs, users can remotely turn the power on and off to individual socket outlets. The switching can be carried out manually or under the control of power management software. This makes it possible, for example, to disconnect non-essential loads in the event of mains supply failure so that UPS runtime and the power supply to critical loads is maximised. It also means that individual servers can be remotely restarted to help restore normal operation after a problem, and that servers can be completely shut down when the demand is light – outside normal working hours, for example.

6. Monitor and manage your power from a single-pane

The latest rack PDUs offer user configurable alerts which work with intelligent power software to trigger automatic migration of virtual servers when, for example, a feed goes down. The software itself integrates with leading virtualisation platforms enabling users to monitor, meter and manage network connected rack PDUs in the same application, together with network, physical server and storage information.

7. Simplify administration of your power system

New generation rack PDUs support mass configuration and updating, which keeps the time needed for power system administration to a minimum. Changes, which occur frequently in today’s dynamic IT environments, can be implemented quickly, efficiently and with minimal risk of error.

8. Save you money on network components

Network connections are essential for all advanced rack PDUs to provide access to their control and monitoring functions. With older types, a separate network port is needed for each rack PDU. This arrangement is expensive – each network port typically costs several hundred Euros to provide – and unwieldy as administrators have to deal with multiple IP addresses. The latest rack PDUs, however, support daisy-chain network connectivity, allowing a single port and just one IP address to be used for multiple rack PDUs. This reduces physical infrastructure installation costs by as much as 75 per cent.

9. Provide you with on-the-spot status information

The best rack PDUs now have integrated displays which can be rotated to suit the installation orientation and which show key status information, such as alarms, right on the rack PDU. This makes it possible to check the operation of the power system almost at a glance, and is an important aid to rapid detection and correction of faults.

10. Provide you with power distribution that’s convenient and flexible

The best rack PDUs are easy to install – especially when the enclosure is sourced from the same supplier as the rack PDU – and they offer a choice of mounting positions. They’re lightweight yet robust and their aluminium chassis not only dissipates heat efficiently but also provides excellent ground conductivity.

In today’s IT environments, where there is constant pressure to maximise performance and reliability while minimising costs, rack PDUs have an essential role to play. Certainly, they distribute power – the clue is in the name – but as we have seen there’s much more they can do to make life easier for hard pressed IT professionals who fully understand their capabilities and potential.