Wolfgang Goretzki, product marketing manager EMEA, Emerson Network Power/Avocent looks at how to become more power efficient

Many data centres today are still not truly switched on to sustainable power management.  Inadequate power management measures are often only revealed when energy bills become surprisingly high. If a rack uses more power than intended the consequences can go way beyond higher bills, from increased risk of downtime to the potential loss of everything connected to it.  It is not that difficult to get on top of power management issues.  Just bear in mind the following ten guiding principles.

1. Correct UPS selection
Uninterrupted Power Supplies (UPS’s) have become commonplace in data centres.  There are three types: the standby or offline UPS (for protection against mains power failure and brief voltage fluctuations for non-critical desktop applications), the line interactive UPS (suitable for other desktop, small network and point-of-sale applications) and the double conversion or online UPS (for use with critical equipment and applications such as servers).  It is important to understand the different levels of protection offered by each. 

2. Power distribution strategy
A power distribution strategy is an important part of running an efficient data centre and subsequent availability of IT equipment.  Traditional single phase methods can be easily exhausted as power density rises. The answer is to use intelligent power distribution units (PDUs).  Available as standalone units or integrated with the power management software, PDUs can monitor, measure, reduce and manage rising power costs while minimising downtimes. Integrated units offer the additional benefit of allowing process-related trends to be tracked over time to keep power consumption, power capacity and power costs of IT equipment in check.

3. PDUs – avoiding square pegs in round holes
PDUs fitted in racks are available in either a vertical or horizontal format. Each has a specific function. The horizontal power distribution units normally have a maximum of ten sockets.  If more than ten sockets are needed the vertical version is right choice.  Care, however, should be taken to ensure there is enough space in the racks for the PDUs so as not to hamper the installation or movement of other IT equipment.

4. Identifying high power users
To accurately determine the power consumption of IT equipment the PDUs must have a measurement capability. Being able to determine the right size for upstream electrical infrastructure can be extremely useful when installing new racks for example.  An ability to optimise the electrical infrastructure enhances the efficiency of the entire power supply chain, which in turn cuts power costs.

5. Reducing downtimes through switching functions
To optimise the availability of all critical equipment in the data centre, PDUs need a switching function as well as a measuring capability.  Switching functions allow equipment to be switched on and off or restarted remotely. They are very important for reducing the downtimes of servers or network equipment that are no longer responding. As well as saving on staff travel costs, being able to control the process remotely allows sockets to be turned on sequentially, thereby avoiding any surges in power supply. This is a major benefit to applications on several interdependent servers that need starting or powering down in a particular order.

6. Automating incident prevention measures
It is not realistic to expect human beings to keep track of everything that is happening in the data centre 24/7. Once again, PDUs with their real-time monitoring of all connected equipment can perform this function.  By setting a threshold value for power and ambient parameters, power overloads and other issues can be averted before they happen through timely detection and alerts.

7. Phasing power supplies
To make best use of the equipment’s integrated redundancy, every single rack should be connected to at least two separate power supplies.  Once the expected loads per rack are known, the next step towards efficient power management comes from selecting the right (single- or three-phase) power supply for each rack.  A three-phase power supply means fewer power supplies are needed per rack, meaning lower the cabling costs, and a more reliable electrical infrastructure (fewer power supplies improve the circulation of air, in turn preventing equipment from overheating).

8. Intelligent cable routing
Tidy cable routing, including installing distributor elements for network cables (known as patch fields) in cabinet systems is a must. These split the individual connections and lend structure to the cabling. Power and data cables must also be kept separate to prevent interference as the networks speed up over time.

9. Simplify power management systems
It takes management software for integrated control of data centre infrastructure.  IT equipment, from network devices and physical servers (with or without integrated service processors) to blade or virtual servers, is best managed centrally from a single console with user-defined views via a browser-based user interface.  Such tools also automate alarms, reporting and auditing of events.

10. Remote power management
Remote administration is an essential part of power management.  Many companies now use “lights-out” or unmanned data centres that reduce the risk of faults and improve safety.  A management system should support an out-of-band function and power distribution units that allow for restarts or activation/deactivation from a remote connection.  All the data needed to power consumption, capacity utilisation and energy costs in remote data centres is managed at a distance from one central console.


Conclusion
Since data centre managers very rarely pay for inadequate power management processes there is often little motivation for change.  But external pressures from management and legislation are building.  In fact there are plenty of measures you can take to help reduce the energy consumption of power-hungry data centres at little cost and effort.  Taking immediate action to reduce energy consumption today rather than waiting until it becomes urgent can bring major financial benefits and help take the lead on environmental issues.