Build for today. Expand on demand.

Build for today. Expand on demand. Modularity in the data center power infrastructure Anderson Hungria, Application Engineer, Eaton Abstract Building the data center to meet the needs of an uncertain future is an expensive and needless exercise in over-engineering. New designs need to be modular, with built-in expansion capabilities. In the data center power infrastructure, modularity can mean: UPSs that scale for added capacity or redundancy, extended battery modules to customize backup runtime, and plug-andplay power distribution components that break down room-level wiring into row- or rack-level modules. This paper looks at the concepts and benefits of modularity in all these elements of the power system. Contents Modularity in the data center power infrastructure... 3 Modularity in power quality systems... 3 What to look for in a modular UPS... 5 Modularity in battery backup... 5 The challenge of battery management in modular configurations... 6 Modularity in power distribution... 6 Conventional panels versus new pluggable rack power distribution... 9 What to look for in modular power distribution... 10 The challenge of monitoring modular power distribution... 10 Case study Modularity for the growing data center... 12 Closing thoughts... 14 About Eaton... 15 About the author... 15

of 15 Build for today. Expand on demand. Modularity in the data center power infrastructure Anderson Hungria, Application Engineer, Eaton The data center one of many at the telecom service provider represented a Utopian vision. The top-of-the-line facility had expansive floor space, twin power utility feeds, and the latest power and cooling systems. Sitting in the middle of the vast data center, like lonely chess pieces, were six racks about four percent of the data center s potential utilization. Build it and they will come, had been the philosophy for establishing the luxuriously over-sized data center, as well as the company s other data centers. But the people didn t come. Ultimately, the service provider joined the annals of good intentions that failed, and their data centers were sold for pennies on the dollar. Even if the people had come, this data center strategy would have been unnecessarily costly. If you overbuild today just to be ready for an uncertain future, you will foot the bills now for space and support infrastructure that may or may not ever be needed. Even if you could justify the cost, the power infrastructure would operate far below capacity and be very inefficient as a result. With the cost of mechanical and electrical equipment, as well as the price of power, this model no longer works, wrote David Cappuccio in IT Modernization: Build Agile Data Centers While Reducing Expenses (Gartner RAS Core Research Note G00156314 -April 18, 2008). However, overbuilding is still the norm today partly because design principles from the old mainframe days still prevail, and partly because data center managers fear running out of capacity. That s not an idle concern; 41.7 percent of data centers will run out of power capacity in 2009-10, according to Uptime Institute (Data Center Capacity and Energy Efficiency, March 2008). That s a scary proposition, especially as new server architectures exponentially increase the demand for power, outlets and redundancy. So what is the best approach? You don t want to pay for excess capacity now, but you don t want to get caught short in the future. Building a whole data center to the highest energy point is expensive and a needless overengineering exercise, wrote Rakesh Kumar and Philip Dawson in The data center as living organism: Why history is not a good guide to the future (Gartner RAS Core Research Note 153516, December 7, 2007). The design principle in Generations 1 and 2 [mainframe and client/server environments] was around a single static structure. New designs need to be modular, with built-in expansion capabilities.

of 15 Kumar and Dawson advocate modularity in the physical space, building out the data center in sections, perhaps 10,000 square feet at a time. Initial capital outlay is lower, and future builds can capitalize on emerging technologies. Cappuccio also recommends clustering IT systems with high power demands in high-density zones, so the power infrastructure can be closely tailored to the needs of a rack or row. There s no need to provide highest power capacity to every square foot of the data center, if only a certain percentage of the racks will need it. Tailoring the power infrastructure in this manner can be readily achieved with today s modular components. But the benefits of modularity are also seen in creating a power system that is as adaptable as the data center needs to be. Virtually every large data center undergoes moves, additions and changes (MACs) once a month or more, according to a Network Computing survey of 474 IT managers (Frequency of MACs, Eaton-sponsored study, July 2006). Frequent change affects 85 percent of mid-sized data centers and 67 percent of small data centers, according to the report. Modular power systems can adapt to such dynamic environments. Build what you need, redeploy later, and expand as needed. Modularity in the data center power infrastructure Modularity means many things to IT managers, such as: incremental data center build-outs in pods, universal racks, blade servers, stackable storage arrays and so on. In the power world, modularity can mean UPSs that scale for added capacity or redundancy, extended battery modules to customize backup runtime, and plug-and-play power distribution components that break down room-level wiring into row- or rack-level modules. For all these interpretations of modularity, the underlying concept is the same: provide a function or process in building-block fashion, and enable users to add, remove or redeploy those building blocks to create variations of the original function or process. Modularity enables you to: Pay only for the functionality you need in the short-term. Plug in new capacity or functionality when the time is right. Expand at your own pace, without starting over with a new platform every time you want to grow or upgrade. Let s take a look at how those concepts and benefits apply in power quality systems, battery backup, and rack-level power distribution. Modularity in power quality systems Historically, many data centers chose a centralized power protection strategy, where a large, standalone UPS powered the entire data center. This approach works when growth can be accurately forecast, but as we ve seen, the data center is a rapidly changing scene. In recent years, many data centers have adopted a zoned strategy, where the data center is divided into zones, each powered by its own UPS. This approach is more scalable than a centralized UPS strategy, and a UPS failure would only affect a single zone, not the whole data center.

of 15 The zone concept advances into the age of modularity with a distributed UPS strategy, where each rack or set of racks has its own UPS and the UPS itself is modular to expand as needed. Redundancy can be established through paralleling, to establish Tier II and higher reliability. In paralleling, two or more UPSs are electrically and mechanically connected to form a unified system with one output either for extra capacity or redundancy. In an N+1 redundant configuration, you would have at least one more UPS module than needed to support the load. As a conjoined system, each UPS stands ready to take over the load from another UPS whenever necessary, without disrupting protected loads. Paralleling provides an excellent solution for matching growth while extending the value of existing UPSs. For instance, the Eaton BladeUPS system delivers 12KW of power protection in a 6U unit expandable to 60kW N+1 in one 19 rack. Paralleling is accomplished using a BladeUPS Bar a plug-and-play bus structure that mounts easily in the back of the equipment rack. Up to six BladeUPS modules can be paralleled to deliver 60kW (with an extra module for redundancy) in one 42U enclosure. A modular UPS, such as the Eaton BladeUPS (pictured) expands in building-block increments. You can start with one 12 kw module and expand to a 60kW configuration (with an extra module for redundancy) as you add IT equipment and need more power. BladeUPS uses the same patented paralleling technology that Eaton developed for much larger systems, with the same philosophy, controls and algorithms. Each UPS module contains its own internal battery trays, built-in static switch, maintenance bypass capability and hot swappable components for ease of replacement or upgrade. The intrinsic reliability of the multi-megawatt parallel systems is preserved in smaller capacity systems. Going modular does not have to compromise reliability.

of 15 What to look for in a modular UPS Small footprint, high power density per rack Ease of installation, without the need for an electrician Ability to install the UPS in your existing racks, if desired Ability for the UPS to share a rack with IT and power distribution equipment Expansion options in building-block increments Hot-swappable components for ease of replacement and upgrade Ready for plug-and-power distribution Paralleling for synchronous function as a single unit Option to expand battery runtime as needed Provisions to ensure reliability of parallel operations Peer-to-peer control rather than master-slave Synchronization to a bypass source rather than a master controller Load sharing does not depend on inter-module wiring Selective tripping to instantly isolate a unit with a fault Modularity in battery backup A typical data center might only resort to battery power for a few minutes a year, or perhaps a few minutes over the entire lifetime of a UPS. But for most data centers, battery backup is still a lifeline for business continuity, and battery demand continues to escalate. That means battery backup systems must be as modular as the UPSs they support. All UPSs must have batteries that support the load for a few minutes during a power outage long enough to gracefully shut down systems or start up a generator. Large centralized monolithic UPS usually need multiple dedicated battery cabinets to achieve even a minimum acceptable runtime. In a modular UPS, internal batteries to each power module provide sufficient system runtime without adding any additional footprint or complexity. However, if you need more runtime than that, look for a UPS that also supports external battery modules. For example, with BladeUPS, you can add a 3U battery extension pack (Extended Battery Module, or EBM), with higher amperage discharge than the internal batteries. These battery modules can be in the same rack as the UPS or a different rack, and plug it into the back of a UPS module. Up to four of these EBMs can be connected to a single unit, increasing runtime from just under 5 minutes to 34 minutes per module at full load, up to an hour or more for lighter loads.

of 15 For true modularity, look for external battery modules that can be placed in the same rack with the UPS, in a completely separate enclosure or even sharing an enclosure with existing IT equipment. This flexibility enables you to place battery modules wherever space is available. Sample runtimes with modular battery packs For a standalone BladeUPS module For a multi-module BladeUPS system The challenge of battery management in modular configurations In traditional parallel configurations, battery management has been a challenge. The entire system has been somewhat at the mercy of the weakest battery in the setup. Here s why Parallel UPS configurations are programmed to share the load evenly among all active UPS modules in the group. Trouble is, although the UPS electronics modules are equally capable of handling equally shared loads, their batteries might not be. Batteries age and deteriorate at different rates. A parallel configuration could easily have a mix of strong batteries and weak ones. If the parallel configuration must resort to battery power during a power outage, some batteries will be up to sharing the task equally, others might not. That reality can trigger a troubling chain of events. The weakest battery is depleted early on, causing its associated UPS module to go into under-voltage alarm and shut down in self-protection. If the remaining units in the parallel configuration cannot support the total load, the whole system will fail, even before completely draining all the available batteries.

of 15 This problem actually still exists with most parallel systems on the market today. In a well-known competitor s system, a fault in a single battery string may affect the performance of the overall system and create a single point of failure, potentially causing a system failure. Eaton considered this domino effect to be an unacceptable risk for modern data centers. The BladeUPS system alleviates this problem by intelligently monitoring the health of each individual battery module and during outage conditions properly adjusting load distribution to take advantage of the strongest batteries, rather than being constrained by the weakest. This innovative feature ensures maximum runtime out of the connected batteries, while protecting UPS inverters from exceeding their rated capacity. For more information about battery load-sharing in parallel BladeUPS systems, visit www.powerware.com and download the free white paper, Are your batteries up to the task? How Eaton maximizes runtime and service life in Eaton BladeUPS systems for high-density data centers. Modularity in power distribution With data center devices smaller than ever often served by dual or triple power supplies a single rack of equipment might produce 40 or more power cords to manage. Power consumption per rack is higher than ever, and continuous uptime is essential. What s the best way to distribute power to racks in the era of modularity? The conventional approach has been to bring power in from the centralized power system (UPS) to a transformer that steps down power to the desired voltage. Power then goes through the main breaker to a panel board, then to power strips in racks. The complexity of this arrangement particularly multiple connections from panel board to power strips makes it expensive, difficult to install, hard to monitor and not particularly resilient to change. A far better alternative is to use a rack power module to provide plug and power distribution from a UPS or panelboard to an enclosure-based power distribution unit (Eaton refers to them as epdus) or directly to IT equipment. Select a rack power module that can deliver power in an organized manner to loads of various voltages, input power cord types and output receptacles supporting a broad range of applications. In order to truly support modularity, this rack power module should be adaptable to serve either of two roles: Primary power distribution from the UPS to a PDU The Eaton Rack Power Module (RPM) can be hardwired, delivers high power (36 kw), provides metering and monitoring, and has 12 poles of distribution breakers essentially bringing the characteristics of a panelboard into a portable 3U box. Secondary power distribution from a PDU or panelboard to IT equipment Where you formerly had many long cable runs (home runs) from a panelboard to enclosures, the rack power module simplifies the cabling and makes it easier to track the power path when adding or changing IT equipment. For either application, the modular approach has fewer cables to manage and greater flexibility, both for changing the IT equipment and the distribution system that powers it.

of 15 Traditional wall-mounted panel boxes yield a tangle of cables and an inflexible infrastructure undesirable attributes in the era of modularity. Enclosure power distribution units (shown in red) distribute power from UPS, panelboard, subfeed or branch circuit breaker to IT equipment. Rack power modules (shown at the top of the racks) can serve dual roles either sending power directly to IT equipment or to additional PDUs to provide more outlets, redundancy and flexibility.

of 15 Conventional panels versus new, pluggable rack power distribution Conventional distribution panels Complexity. The sheer number of cables exiting a conventional distribution cabinet adds complexity and confusion. The length of each home run cable adds expense. Dependence. Almost always requires the services of an electrician to construct/install power cables any time the rack configuration changes. Limits flexibility for rearranging and upgrading IT equipment. Potential overloads. Load balancing is difficult, and if ignored, can cause nuisance overload alarms from the UPS, and tripped breakers, which cause load losses. Rack Power Module Simplicity. Power distribution is well organized, and it is easy to follow the power path to the load, enabling better cable management. Self-reliance. Once the main connection to the UPS is made, the plug and power architecture enables you to change and rearrange equipment in the rack without an electrician. Assurance. Load balancing is somewhat automated by the use of three phase inputs and either three-phase outputs or balanced single-phase output receptacles. epdu Plug-and-play. Streamline power cabling at the rack level while enabling technicians to plug and unplug IT equipment at will without an electrician. Do-it-yourself. epdus can snap into key-type slots in racks, so data center technicians can install, move and change them very easily, without using any tools. Visibility. New epdus offer local and remote monitoring to give visibility into power conditions and alert notifications at the circuit level. Modern enclosure-based PDUs can be installed in many locations and can be removed and redeployed as needed, making it easy to support moves, adds and changes in IT systems.

of 15 What to look for in modular power distribution Compact size, such as 3U for a rack power module, 1U or 2U for an enclosure-based PDU Ability to mount the device anywhere, not just in one vendor s rack or a specified slot Installation options that conserve valuable U space and support easy cable management Ability to easily move, redeploy and swap out epdus without tools or an electrician Ability to install epdus horizontally or vertically, multiple units per rack Display of load currents for load balancing and protection during moves, adds and changes Ability to monitor epdus over the network through IP communication Sufficient power capacity and receptacles to meet projected needs for 12-18 months Additional functionality, such as remote control or receptacle-level metering, if possible The challenge of monitoring modular power distribution Data center managers could rightfully wonder if modular power distribution might be more difficult to monitor. After all, there will be dozens or even hundreds of epdus to track, compared to a few power distribution racks. That concern is fair enough. In the past, managing all those rack-level power distribution devices has been problematic, for a couple of reasons: With older or very basic epdus, there is typically no visibility into current flow at this level. If an overload condition or tripped circuit is imminent, customers wouldn t see it coming. With newer epdus networked over the company LAN, users typically have to point their Web browsers to each device to see its status a time-consuming and tedious proposition. Those compromises are no longer necessary. With the latest epdus and software, you can monitor and manage network-connected power distribution components at the rack level via one Web-based user interface and one IP address. Straightforward and budget-friendly software is available to aggregate power data from a virtually unlimited number of epdus and UPSs on an IP network into a cohesive, enterprise-wide view. Going modular doesn t have to compromise visibility; in fact, it extends visibility further to the edge of the distribution system.

of 15 How does modularity affect reliability? Traditional thinking held that when you adopt modular components, you increase component count, and with more components comes more risk of component failure. Modularizing a system for instance, using a bank of 12kW UPS modules instead of a larger, stand-alone UPS system would certainly increase the number of internal electronic components and connectors. Could more parts translate into more potential points of failure? Not so, with other advantages inherent in modern UPS designs: Redundant modules operating in parallel can cover for an individual module that is removed from service, without affecting overall system performance. Whereas older, monolithic UPSs were difficult to move and replace, small hot-swappable modules can be removed and replaced by one or two technicians, often without assistance from the vendor. Modular component tend to be manufactured in much greater quantities than non-modular systems, so they benefit from the quality improvements of more mass production, less manual intervention, during manufacture. Replacement components, such as electronics module and battery are more easily available and cheaper to maintain.

of 15 Case study Modularity for the growing data center The following illustrations show how modularity enables the power infrastructure for a data center to grow gracefully in increments as the data center grows. There s no need to overbuild today for future needs. The modular approach preserves the value of original investments even as IT racks evolve from low-density (requiring 4-5 kw) to medium density (8 to 10 kw) to high density (15+ kw), and as overall power requirements double or triple. Modular data centers should also be able to support a mix of low-, mid- and high-powered enclosures as new IT equipment is installed. Legend: In the diagrams, racks of different power densities are shown in different colors. Phase I: A modular UPS provides 36 kw (N+1) to serve nine low-density racks. RPMs streamline home run cabling. Power distribution units provide the outlets needed for dual- and triple-corded loads.

of 15 Phase II: As the data center adds more enclosures and more power-hungry equipment to go in them, more UPS and battery modules are easily added to any existing enclosure or a new one. Phase III: Additional UPS modules have been added to deliver the 180 kw required for this configuration. Rack-mounted power modules and PDUs flexibly distribute power within and among enclosures.

of 15 Closing thoughts Modularity enables the data center to meet tomorrow s needs without overbuilding (and overpaying) for it today. Modular components are smaller and easier to install a real plus since power distribution equipment may be reinstalled several times over its service life to keep pace with moves, adds and changes. Modular components such as rack-mounted UPSs, battery modules and power modules can be designed to fit into existing enclosures in the data center. You don t want to use up valuable footprint for standalone equipment that doesn t harmonize with the rest of the data center line-up. Monitoring capabilities at all levels of the modular power infrastructure ensure that moves, adds and changes will not bring unwelcome surprises in terms of overload conditions or tripped circuits. Modular components in the power infrastructure make it easier to support modularity in IT equipment. Rack power modules and enclosure-based PDUs bring power distribution closer to the endpoint, so it is easier to find the power and receptacles needed for all those multi-corded IT components. Plan ahead for modularity. When evaluating components for the data center power infrastructure, look for the ability to support modular expansion and redeployment later. There may be some incremental additional investment such as a parallel bus bar in an enclosure to support a modular UPS, for example but once that initial setup is done, you only have to buy additional modules as needed, plug them in and go. There are more options than ever to capitalize on modular architectures to tailor the power system for your unique data center requirements and the velocity of change. As you plan to upgrade power systems or build a new facility, seek to create a power infrastructure that is as adaptable as the IT infrastructure must be.

of 15 About Eaton Eaton Corporation is a diversified manufacturing company ranked among the largest Fortune 500 companies. The electrical group is Eaton s largest division and is a global leader in electrical control, power distribution, power quality, automation, and monitoring products and services. Eaton s global electrical brands, including Cutler-Hammer, MGE Office Protection Systems, Powerware, Holec, MEM, Santak and Moeller, provide PowerChain Management solutions to serve the power system needs of the industrial, institutional, government, utility, commercial, residential, IT, mission critical and OEM markets worldwide. PowerChain Management solutions help enterprises manage the power system as a strategic, integrated asset a more energy efficient, resilient and adaptable infrastructure. Eaton has 81,000 employees and sells products to customers in 150 countries. For more information, visit. www.eaton.com About the author Anderson Hungria is an application engineer for Eaton in Raleigh, North Carolina. You can reach him at AndersonHungria@Eaton.com.