Information Systems & Technology

We consider the use of fuel cells for powering data centers, based on benefits in reliability, capital and operational costs, and reduced environmental emissions. Using fuel cells effectively in data centers introduces several challenges and we highlight key research questions for designing a fuel cell based data center power distribution system. We analyze a specific configuration in the design space to quantify the cost benefits for a large scale data center, for the most mature and commonly deployed fuel cell technology, achieving over 20% reduction in costs using conservative projections.

The IT industry is the fastest growing sector in US energy consumption. Improving data center energy efficiency is a pressing issue with significant economic and environmental consequences. Heat distribution is a key operational parameter that affects data center cooling and energy consumption. However, typical data centers lack effective finegrained sensing systems to monitor heat distribution at a large scale. In this paper, we motivate the use of sensor networks as a dense instrumentation technology to understand and control cooling in data centers. We present Microsoft Research Genomote sensors designed for data center monitoring, and the RACNet for reliable data acquisition. We describe lessons learned from early pilot deployments, and discuss architectural and technical challenges in developing data center sensor networks.

In this paper, we argue that servers can be sent to homes and office buildings and used as a primary heat source. We call this approach the Data Furnace or DF. Data Furances have three advantages over traditional data centers: 1) a smaller carbon ...

Modern data centers consume large amounts of electricity, resulting in high operational costs. The efficiency of a data center power distribution system can be increased and the operational cost reduced if the number of power conversion stages can be minimized and more efficient converters, such as wide bandgap converters, are used. This can be achieved by using dc distribution voltage at the rack level by eliminating extra conversion stages. In this paper, benchmarks for both ac and 380-V dc data centers were developed and efficiency analyses were performed for an entire year. The impact of integrating photovoltaic (PV) systems into the data centers has also been analyzed in both cases in terms of efficiency. The results show that 380-V dc data centers are more efficient than ac data centers with and without PV integration. Furthermore, the reliability of an ac system was compared with a 380-V dc architecture with Tier-IV standard. Monte-Carlo simulations were used to perform reliability analyses for different levels of redundancy in the uninterruptible power supply system for both cases. The simulation results showed that the 380-V dc distribution system had a higher level of reliability than the ac distribution system in data centers.

Off-grid power generation has been demonstrated in data centers through the deployment of site-specific centralized power plants utilizing gas turbine or fuel cell-based power generation. Because power is centrally generated, power distribution requires a high voltage power grid within the data center with its ancillary storage and conditioning requirements and equipment. An alternative approach is a completely decentralized distributed power generation system in which fuel cells deployed within individual server racks provide power localized to that rack only. Among other advantages, such an approach also greatly increases the ability to modulate and control power to individual rack units. Because the Solid Oxide Fuel Cells (SOFC) proposed in this approach are aircooled and have extremely high air exhaust temperatures, of order 800 o C, the optimal energy efficient design of an overall localized fuel-cell power generation system should also consider the opportunities to recover and re-use the waste heat. This paper reports on the development of a coupled thermal-electrical model of a thermoelectric generator (TEG) based energy recovery system operating between the fuel cell hot exhaust air temperature and a warm water cooling system deployed within the rack for server cooling. The power generation system consisted of a TEG module sandwiched between a hot air heat exchanger and a colder water based heat exchanger. The design of the TEG module for maximum power generation is heavily coupled with thermal and electrical conditions. Distribution of temperature on generator surfaces change the optimum design, hence the optimization of generator system required co-optimization with the design of the heat exchangers. This paper will present the results of a co-optimization study considering the effects of thermal parameters such as exhaust gas mass-flow-rate and temperature, cooling water volumetric-flow-rate and temperature, hot-and cold-flow parallel and counter-flow arrangements, as well as the thermal-electrical considerations in the TEG design including the design of the Thermo-Electric junctions, fractional area coverage of thermoelectric elements, and substrate thickness. KEY WORDS: waste heat recovery, server rack, cooling water, fuel cell, TEG module, thermoelectric model NOMENCLATURE A area/ total surface area, m 2 Bi Biot number D channel diameter, m p c specific heat capacity at constant pressure, kJ/kg K d el electrode thickness, m F TED module filling factor H height/ height of the fin, m h convection heat transfer coefficient, kW/m 2 K k thermal conductivity of the base of heat-sink or cold

Typically, improving data center availability requires designing in more infrastructure; the antithesis of reducing costs. Is there a way to cut infrastructure, cost and emissions while improving energy efficiency and server availability? We consider and evaluate the integration of fuel cells with IT hardware with various architectural designs, essentially collapsing the entire energy supply chain, from power plant to power supply unit, into the confines of a single server cabinet. In this paper, we propose a distributed power architecture for fuel cell powered data centers to achieve high reliability and efficiency. We describe the distributed fuel cell power system design and the system components. We experimentally validate the design and demonstrate the use of a 10kW Proton Exchange Membrane Fuel Cell (PEMFC) stack and system as the distributed power source to power a server rack, eliminating the power distribution system in the data center and the grid outside of the data cente...

Fuel cells are a promising power source for future data centers, offering high energy efficiency, low greenhouse gas emissions, and high reliability. However, due to mechanical limitations related to fuel delivery, fuel cells are slow to adjust to sudden increases in data center power demands, which can result in temporary power shortfalls. To mitigate the impact of power shortfalls, prior work has proposed to either perform power capping by throttling the servers, or to leverage energy storage devices (ESDs) that can temporarily provide enough power to make up for the shortfall while the fuel cells ramp up power generation. Both approaches have disadvantages: power capping conservatively limits server performance and can lead to service level agreement (SLA) violations, while ESD-only solutions must significantly overprovision the energy storage device capacity to tolerate the shortfalls caused by the worst-case (i.e., largest) power surges, which greatly increases the total cost o...

Datacenters often are a power utility's largest consumers, and are expected to participate in several power management scenarios with diverse characteristics in which Energy Storage Devices (ESDs) are expected to play important roles. Different ESD technologies exist, including little explored technologies such as flow batteries, that offer different performance characteristics in cost, size, and environmental impact. While prior works in datacenter ESD literature have considered one of usage aspect, technology, performance metric (typically cost), the whole three-dimensional space is little explored. Towards understanding this design space, this paper presents first such study towards joint characterization of ESD usages based on their provisioning and operating demands, under ideal and realistic ESD technologies, and quantify their impact on datacenter performance. We expect our work can help datacenter operators to characterize this three-dimensional space in a systematic manner, and make design decisions targeted towards cost-effective and environmental impact aware datacenter energy management.

The IT industry is the fastest growing sector in US energy consumption. Improving data center energy efficiency is a pressing issue with significant economic and environmental consequences. Heat distribution is a key operational parameter that affects data center cooling and energy consumption. However, typical data centers lack effective finegrained sensing systems to monitor heat distribution at a large scale. In this paper, we motivate the use of sensor networks as a dense instrumentation technology to understand and control cooling in data centers. We present Microsoft Research Genomote sensors designed for data center monitoring, and the RACNet for reliable data acquisition. We describe lessons learned from early pilot deployments, and discuss architectural and technical challenges in developing data center sensor networks.

The topic of this paper addresses the mysterious and understudied origin story of The Honorable Order of Kentucky Colonels. When Kentucky's first governor, Isaac Shelby, began carving out the new state of Kentucky by forming and strengthening the militia. Shelby would eventually meet a young Charles Todd serving under General James Winchester who would go on to marry Shelby's daughter and, legend has it, become the first honorary Colonel that would spawn the Order of the Kentucky Colonels. This paper addresses the period from the inception of Kentucky to the War of 1812 as it is concerned with the history surrounding Governor Shelby and the young militia Officer Todd. This paper will argue that though disputed, the official history of the Kentucky Colonels is arguably correct.

This paper presents a comprehensive guide to implementing threat modeling in cybersecurity. Threat modeling involves identifying, analyzing, and assessing potential threats to a computer system, network, or organization's digital assets. It systematically evaluates the vulnerabilities and risks associated with an organization's technology infrastructure, data, and business processes, emphasizing the importance of preparing and documenting a threat modeling approach to understand potential threats, their probability of success, and the associated risks and highlighting the benefits of threat modeling, such as identifying potential threats like malware, unauthorized access, data breaches, and system failures.
Additionally, the paper discusses the challenges of implementing a dynamic threat modeling program, including achieving buy-in across the organization, time and resource commitments, and addressing knowledge gaps.

Network segmentation is a cornerstone of modern cybersecurity aimed at enhancing security, performance, and management by dividing networks into smaller, isolated sections. Traditional methods, such as VLANs and firewalls, face scalability, complexity, and flexibility limitations. Ethernet Virtual Private Network (EVPN), combined with Virtual Extensible LAN (VXLAN), represents a significant advancement, leveraging BGP for control plane operations and encapsulating Layer 2 frames over Layer 3 networks. This paper examines the architecture and operation of EVPN-VXLAN, highlighting its benefits in contemporary data center and enterprise network environments, including improved security, optimal path utilization, and enhanced regulatory compliance. Additionally, it outlines strategies for securing EVPN-VXLAN segmentation, ensuring robust protection against cyber threats.

This course introduces the fundamentals of computer systems and the role of information processing in today's business environment. An overview is presented of information systems, systems development, operating systems and programming, database management, networking and telecommunications, and the Internet.