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Copyright of Elektronik Industrie is the property of Hüthig GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

On-demand provisioning of computing resources using the network over the Cloud consumes a tremendous amount of energy. The energy consumed does not scale out efficiently with the computational use of the resources. A large portion accounts for the power consumption to drive the hardware and cooling facilities for the hardware resources. Nowadays, energy and power consumption have become the most critical concerns in data centers. This work highlights a novel technique to achieve energy efficiency through server consolidation to address the abovementioned situations by effectively scheduling Virtual Machines (VMs) onto the servers and rescheduling active VMs upon deletion of existing VMs through cold migration. An advanced technology, i.e. Wake on LAN (WoL), is employed through power wake for dynamic and wake up of the servers on private Cloud. Compared to existing models, the proposed approach's maximum estimated energy and power saved are experimentally verified to be 54% and 50%, respectively. [ABSTRACT FROM AUTHOR]

Cloud computing technology is widely used in many industries to build a large-scale data center. One of the main challenges in this technology is to minimize the energy utilization in data centres. The quality of service is remarkably obsessed with percentage of power utilization in cloud centres. Many methods have been explored to minimize the energy consumption and for effective Virtual Machine (VM) migration. But failed to attend the significant outcomes in migration and consolidation problems. Consolidation of VM into the minimal number of physical machines is considered one of the best solutions to consume minimum power. This research proposed an Energy Migration Optimized using Enhanced Pelican Remora (EMOEPR) for achieving the suitable placement of VM into minimum possible physical machine to diminish the number of overload hosts as much as possible. Also, it minimizes the energy consumption without violating service level agreement. The proposed method is simulated using Cloudsim Toolkit. The experimental procedure done on different workloads with various sizes of VM and PM, shows that does not affect service level agreement and outperforms compared with the existing techniques. The proposed method reduced 5% energy consumption, 22.62% of VM migrations, 8.62% of service level agreement violation when compared with the existing techniques. [ABSTRACT FROM AUTHOR]

Summary: Virtual machine (VM) consolidation is to assign a set of VMs requested by operators to the physical machines (PMs) in the data centers so that certain cost, profit or performance objective is optimized, subject to the PMs resource capacity constraints. It is an important mean to decrease the total power consumption by reducing the number of active physical machines (PM) in a cloud. In this context, most of the existing solutions rely on highly frequent live migration to reduce the number of active physical machines. However, live migration is a high resource consumption and time‐consuming operation, thus, frequent use of live migration not only increases energy consumption but also affects the stability of the physical machine, which in turn affects the services on the virtual machine. Reducing the number of active physical machines while reducing the number of live migrations is a major challenge in the face of massive fluctuating virtual machine loads. In order to solve this problem, in this paper, we present a VM consolidation algorithm for predictable loads (VCPL) to reduce the live migration operations. First, we present a cyclic usage prediction (CUP) method to predict the load in a whole cycle (a day) of a VM. Then, we separate the VMs with stable and cyclic load out from others and consolidate them to PMs by using VCPL to make sure each PM has a stable load. Thus, energy can be reduced by avoiding most of live migration operations, and the stability of the data center can be observably improved. We evaluate our solution through simulations on real‐world workloads, the results show that, 66% of long‐term VMs have stable and cyclic loads and are predictable, by using VCPL, the live migration operations occurring on the PMs which accommodate those VMs can be reduced significantly than other solutions. [ABSTRACT FROM AUTHOR]

The highlighted energy consumption of Internet data center (IDC) in China has become a pressing issue with the implementation of the Chinese dual carbon strategic goal. This paper provides a comprehensive review of cooling technologies for IDC, including air cooling, free cooling, liquid cooling, thermal energy storage cooling and building envelope. Firstly, the environmental requirements for the computer room and the main energy consumption items for IDC are analyzed. The evaluation indicators and government policies for promoting green IDC are also summarized. Next, the traditional cooling technology is compared to four new cooling technologies to find effective methods to maximize energy efficiency in IDC. The results show that traditional cooling consumes a significant amount of energy and has low energy efficiency. The application of free cooling can greatly improve the energy efficiency of IDC, but its actual implementation is highly dependent on geographical and climatic conditions. Liquid cooling, on the other hand, has higher energy efficiency and lower PUE compared to other cooling technologies, especially for high heat density servers. However, it is not yet mature and its engineering application is not widespread. In addition, thermal energy storage (TES) based cooling offers higher energy efficiency but must be coupled with other cooling technologies. Energy savings can also be achieved through building envelope improvements. Considering the investment and recovery period for IDC, it is essential to seek efficient cooling solutions that are suitable for IDC and take into account factors such as IDC scale, climate conditions, maintenance requirements, etc. This paper serves as a reference for the construction and development of green IDC in China. [ABSTRACT FROM AUTHOR]

Data centres, though a necessary part of modern society, are being stigmatised for consuming vast amounts of electricity for their operational and cooling needs. Due to Ireland's reliance on fossil fuels to meet the increased energy demand of data centres, the data centres are contributing significantly to Ireland's total carbon emissions. As much of this energy is expelled from data centres as waste heat energy, the potential for recycling some of this wasted heat energy was explored using environmentally friendly systems from recent publications. The recovered waste heat energy was applied in a vertical farming system, and the benefits of this waste heat to the vertical farm were analysed and quantified in two scenarios. Using conservative estimates, it was predicted that each vertical farm could be between 5–23% the size of the data centre and produce enough food to feed between 14–61 adults their daily calorie needs, and between 13–58 people their daily fresh produce requirements, depending on the scenario applied. For a more accurate prediction, each vertical farm would have to be assessed on a case-by-case basis, as there is no current research in this area. However, there was not enough data available on Irish data centres to perform these calculations. [ABSTRACT FROM AUTHOR]

The need to reduce data center operational costs has necessitated siting cloud computing platforms in cold locations such as the stratosphere. The stratosphere has also been found to play an important role in understanding life origins as it hosts life forms. The use of stratosphere based computing platforms however requires the hosting of multiple server payloads (requiring high energy consumption) at a higher altitude. In addition, smaller server payloads lead to smaller sized stratospheric computing platforms (SCPs) which limit interaction with stratospheric organisms. However, these challenges are not considered when designing SCPs. Hence, there is a risk of wrongly evaluating the power usage effectiveness (PUE) associated with SCPs. In addition, there is a risk of installing and deploying large sized SCPs thereby leading to contamination and limiting research potential on studying life forms. The research being presented proposes an intelligent architecture enabling the identification, selection and use of only light weight servers aboard SCPs. The incorporation of the intelligent architecture is observed to enhance the PUE by 43.9%. In addition, the use of the intelligent architecture is noted to enhance the overall PUE by 59.6% for hosting altitudes spanning the low to mid stratosphere regions. In addition, the reduction in server weight by an amount exceeding 92% is noted by simulations to enable the realization of a PUE that is close to the ideal value of unity. [ABSTRACT FROM AUTHOR]

Based on the cooling load of the data center in the Pearl River Delta region and the time-of-use tariff policy, a water storage cooling system was selected as the energy storage solution. The water cold storage system and operation control plan were optimized, and the operation and energy consumption of the water cold storage system were analyzed for typical days, months, and whole year. Through economic analysis of its operation, it was found that the annual cooling operation cost was reduced by 25. 78%, further verifying the feasibility of the water storage plan. Overall, it is shown that the water cold storage system can operate efficiently while ensuring the demand for indoor end load, and has a good effect of “peak-load shifting effect” and reducing cooling electricity costs. [ABSTRACT FROM AUTHOR]

Data center is one of the indispensable infrastructures in the modern information society, however, its high energy consumption and carbon emission have become an urgent problem. In order to reduce the large energy consumption of data centers in hot and humid areas due to mechanical cooling and air-conditioning systems, the operation of an indirect evaporative cooling (IEC) air-conditioning system was simulated in a hot and humid area data center based on Matlab and the Energy Plus platform, its annual energy consumption was evaluted. The impact of solar assisted dehumidification (LDD) system on the three operation modes and the performance of IEC air-conditioning system were also investigated. The results show that the IEC air-conditioning system can achieve 16.5% annual energy saving intensity compared to a conventional mechanical cooling system, and that the addition of an LDD unit can increase the wet mode operating time of the IEC air-conditioning system by 35.9% and reduce the system energy consumption by 20.1%. Therefore, IEC air-conditioning systems have significant energy-saving advantages in hot and humid data centers and can significantly improve the operational efficiency and sustainability of data center air-conditioning systems. [ABSTRACT FROM AUTHOR]

Aiming at the difficulty of accurately reflecting the actual effect of the engineering application of the data center’s energy consumption evaluation results. In this paper, on the basis of the existing data center energy efficiency evaluation index, from the data center, data center air conditioning system, indirect evaporative cooling air conditioning equipment in three dimensions, respectively, put forward the data center indirect evaporative cooling air conditioning PUE coefficient, data center air conditioning energy utilization efficiency, indirect evaporative cooling air conditioning equipment refrigeration density and other evaluation indicators. Using the new evaluation indexes as well as the assignment analysis method, case studies were conducted on data centers with different cooling systems. The results show that the indirect evaporative cooling air-conditioning system has obvious advantages of power and water saving compared with the traditional chilled water system, but its refrigeration density index still has much room for improvement. The proposal of the new index improves the energy efficiency evaluation system of data centers and can lead to further improvement of the performance quality of related air conditioning products. [ABSTRACT FROM AUTHOR]

To reduce energy consumption in data center cooling systems and ensure the healthy and rapid development of data centers, this study focuses on the cooling system of a data center in Guangzhou. Addressing the efficiency variations of chillers at different Partial Load Rates (PLR), a novel model predictive control method is proposed. The study employs Gaussian process regression to establish a chillers’ operational efficiency model and utilizes Long ShortTerm Memory (LSTM) neural networks to create an outdoor wet bulb temperature time series prediction model. Based on the data center cooling load and the prediction of outdoor wet bulb temperature, the cooling system’s chilled water storage and discharge modes, storage and discharge capacity, the number of chillers, and the PLR are adjusted. This adjustment aims to partially decouple the demand and supply sides, resulting in the chillers being operated in high efficiency or turned off, thereby reducing the operational energy consumption of the cooling system. To evaluate the performance of this strategy, annual energy consumption simulations were conducted, compared to the traditional rule-based control strategy, the model predictive control strategy reduced the overall energy consumption by 3.13% and operating costs by 3.33%. [ABSTRACT FROM AUTHOR]

The growing smart cities in urban areas are becoming more intelligent day by day. Massive storage and high computational resources are required to provide smart services in urban areas. It can be provided through intelligence cloud computing. The establishment of large-scale cloud data centres is rapidly increasing to provide utility-based services in urban areas. Enormous energy consumption of data centres has a destructive effect on the environment. Due to the enormous energy consumption of data centres, a massive amount of greenhouse gases (GHG) are emitted into the environment. Virtual Machine (VM) consolidation can enable energy efficiency to reduce energy consumption of cloud data centres. The reduce energy consumption can increase the Service Level Agreement (SLA) violation. Therefore, in this research, an energy-efficient dynamic VM consolidation model has been proposed to reduce the energy consumption of cloud data centres and curb SLA violations. Novel algorithms have been proposed to accomplish the VM consolidation. A new status of any host called an almost overload host has been introduce, and determined by a novel algorithm based on the Naive Bayes Classifier Machine Learning (ML) model. A new algorithm based on the exponential binary search is proposed to perform the VM selection. Finally, a new Modified Power-Aware Best Fit Decreasing (MPABFD) VM allocation policy is proposed to allocate all VMs. The proposed model has been compared with certain well-known baseline algorithms. The comparison exhibits that the proposed model improves the energy consumption by 25% and SLA violation by 87%. [ABSTRACT FROM AUTHOR]

With the launch of the "Channel Computing Resources from the East to the West" project, Beijing-Tianjin-Hebei region, as a national integrated big-data center system, has established a Zhangjiakou data center cluster and continuously optimized the regional computing power layout. Beijing has been accelerating the construction of a global digital economy benchmark city since 2021, committed to forming a collaborative development pattern of computing power integration, and achieving a globally leading density of data centers. The core industry of Beijing's digital economy has strong fundamental advantages, but as a high-energy consuming industry, data centers cannot fully meet real-time computing power needs solely relying on the local infrastructure construction in Beijing. Therefore, this paper explored the promoting role of the Beijing-Tianjin-Hebei national integrated big-data center system in the construction of a global digital economy benchmark city in Beijing through channels such as computing power resource sharing, green energy consumption support, and industrial development collaboration. Based on this, it analyzed the challenges that still exist in current regional collaboration. [ABSTRACT FROM AUTHOR]

The cloud computing center can dynamically respond to various needs, schedule computing resources, and provide users with convenient IT services. As the demand for cloud computing services continues to increase, the scale of the data center is getting larger and larger, and the problem of high energy consumption of equipment is becoming more and more prominent. Therefore, building a green data center is key to ensuring the development of the technology industry. Virtual machine online migration technology has been widely used in energy consumption management, which plays an important role in the energy‐saving management of large‐scale data centers. Considering the problem of energy consumption in a multi‐data center environment, a cross‐data center virtual machine migration strategy is proposed, EVMA. First, the target data center of the virtual machine migration is determined according to the bandwidth between data centers, and then the overload host and virtual machine selection strategy is determined according to the historical CPU load. The experimental results showed that the algorithm had a good performance in reducing the energy consumption of the data center and ensuring the quality of service. [ABSTRACT FROM AUTHOR]

The digital transition that drives the new industrial revolution is largely driven by the application of intelligence and data. This boost leads to an increase in energy consumption, much of it associated with computing in data centers. This fact clashes with the growing need to save and improve energy efficiency and requires a more optimized use of resources. The deployment of new services in edge and cloud computing, virtualization, and software-defined networks requires a better understanding of consumption patterns aimed at more efficient and sustainable models and a reduction in carbon footprints. These patterns are suitable to be exploited by machine, deep, and reinforced learning techniques in pursuit of energy consumption optimization, which can ideally improve the energy efficiency of data centers and big computing servers providing these kinds of services. For the application of these techniques, it is essential to investigate data collection processes to create initial information points. Datasets also need to be created to analyze how to diagnose systems and sort out new ways of optimization. This work describes a data collection methodology used to create datasets that collect consumption data from a real-world work environment dedicated to data centers, server farms, or similar architectures. Specifically, it covers the entire process of energy stimuli generation, data extraction, and data preprocessing. The evaluation and reproduction of this method is offered to the scientific community through an online repository created for this work, which hosts all the code available for its download. [ABSTRACT FROM AUTHOR]

The rise in internet user demand is a major factor in the expansion of infrastructure and the upsurge in energy use in cloud, colocation, and some business data centres. The advent of 5G has compounded the situation, as it substantially gives room for many new types of digital services, resulting in a need for richer media formats and higher resolution content which consume a lot of energy when no scaling method is applied. Services such as email, data storage and retrieval and other cloud services also require a lot of high energy consumption which eventually result into carbon(IV) oxide (CO) emissions to the environment. This research therefore, focuses on 2 lowering the energy usage of a data centre with heterogeneous power awareness either in an idle server state or high-performance state using a novel hybridized algorithm called "DyVoFesLoReMu", comprising Dynamic Voltage Frequency Scaling (Dvfs) and a modified Local Regression Minimum Utilization (LrMu). A real dataset (workload) obtained online from PlanetLab consisting of hosts and Virtual Machines (VM) was simulated on a data center in CloudSim 3.0.3. Tool kit with preset parameters consisting of VM Allocation Policy and VM Selection Policy was used. The tool kit was utilised to create cloud infrastructure and simulate the essential features of a cloud environment. The Cloudsim was installed on Eclipse Integrated Development Environment (IDE) 2019 version on Windows 10 operating system. The hybridized algorithm was compared with other five (5) existing energy reducing algorithms and it was found to be more efficient with a range of 41-90% reduction in energy usage from the ten days workload traces and in comparison with the existing algorithms used for the simulation. [ABSTRACT FROM AUTHOR]

With the increased penetration of cloud computing and virtualization, a plethora of internet of things devices have been deployed globally. As a result, computationally intensive tasks are transmitted from the edge towards the centralized cloud for processing that leads to increased energy utilization in the cloud data centers while at the same increasing significant latency for critical applications. Recent years have witnessed a paradigm shift from centralized cloud computing towards mobile edge computing (MEC), where computational tasks are offloaded at the edge servers near user equipment (UE). This paradigm leads to lowering the energy utilization in the cloud data centers, along with low latency for UE and efficient resource utilization at the edge. In this context, the scale and complexity of the MEC networks is drastically increasing and, consequently, finding effective energy-efficient solutions for computational task offloading and resource allocation in MEC networks has become an ambitious task. To address the aforementioned challenges, this work surveys the state of the art in different categorizations of algorithm-based computational task offloading and resource allocation strategies focusing on energy utilization. It also provides a detailed cross-comparison of existing strategies in terms of their implementation specifications. Additionally, this paper also highlights open challenges and potential future research directions to facilitate efficient task offloading and resource allocation at the edge with reduced energy consumption at the centralized data centers. Our work also paves the way for the deployment of critical applications at the edge that require low latency and high service quality guarantees. [ABSTRACT FROM AUTHOR]

In 2018, Norway promoted itself as a 'Datacentre Nation'. In terms of low cost, renewably generated sources of electricity and low ambient temperatures, Nordic countries and the data centre sector are potentially mutual beneficiaries – yet, there are also negative impacts associated with the necessary electric power production. With this as a starting point, for Norway and Iceland, we explore how data centre proponents promulgate similar techno-environmental imaginaries, but achieve differing degrees of stabilisation. To this end, we use three sources of imaginaries relating to data centre development in Iceland and Norway: those implicit in promotional imagery originating within the countries concerned; those implicit in international newspapers, as indicative of external perceptions; and those implicit in focus groups with the Norwegian and Icelandic public. We show how data centre advocates deploy visual imagery to create a promotional techno-environmental imaginary that marries nature with the digital in a symbiotic form, and we observe that this is largely consistent with the more mundane international imaginary of Norwegian data centres. For Iceland, however, the external imaginary is dominated by associations of excess energy consumption by bitcoin mining. For the publics questioned, there are multiple imaginaries of data centres, with significant notes of moral and other forms of scepticism. Looking ahead, we suggest that for long-term stabilisation of positive data centre imaginaries, conducive to investment, the capacity of Iceland and Norway to equitably supply sufficient renewable power will need to be addressed as a matter of urgency. [ABSTRACT FROM AUTHOR]

Cloud computing offers internet-based services to customers. Infrastructure as a service offers consumers virtual computer resources including networking, hardware, and storage. Cloud-hosting startup delays hardware resource allocation by several minutes. Predicting computer demand will address this problem. The performance comparison showed that combining these algorithms was the best way to create a dynamic cloud data centre that efficiently used its resources. One of these challenges is the need of practicing effective SLA management in order to prevent the possibility of SLA breaches and the repercussions of such violations. Exponential Smoothing and Artificial Neural Network (ANN) models in terms of managing SLAs from the point of view of cloud customers as well as cloud providers. We proposed an Exponential Smoothing and Artificial Neural Network model (ESANN) for SLA violation and predict the CPU utilization from time series data. This model includes SLA monitoring, energy consumption, CPU utilization, and accuracy prediction. Experiments show that the suggested approach helps cloud providers reduce service breaches and penalties. ESANN outperforms Exponential Smoothing, LSTM, RACC-MDT, and ARIMA by attaining 6.28%, 16.2%, 27.33%, and 31.2% on the combined performance indicator of Energy SLA Violation, which measures both energy consumption and SLA compliance. [ABSTRACT FROM AUTHOR]

The IoT has connected a vast number of devices on a massive internet scale. With the rapid increase in devices and data, offloading tasks from IoT devices to remote Cloud data centers becomes unproductive and costly. Optimizing energy consumption in IoT devices while meeting deadlines and data constraints is challenging. Fog Computing aids efficient IoT task processing with proximity to nodes and lower service delay. Cloud task offloading occurs frequently due to Fog Computing's limited resources compared to remote Cloud, necessitating improved techniques for accurate categorization and distribution of IoT device task offloading in a hybrid IoT, Fog, and Cloud paradigm. This article explores relevant offloading strategies in Fog Computing and proposes MCEETO, an intelligent energy-aware allocation strategy, utilizing a multi-classifier-based algorithm for efficient task offloading by selecting optimal Fog Devices (FDs) for module placement. MCEETO decision parameters include task attributes, Fog node characteristics, network latency, and bandwidth. The method is evaluated using the iFogSim simulator and compared with edge-ward and Cloud-only strategies. The proposed solution is more energy-efficient, saving around 11.36% compared to Cloud-only and approximately 9.30% compared to the edge-ward strategy. Additionally, the MCEETO algorithm achieved a 67% and 96% reduction in network usage compared to both strategies. [ABSTRACT FROM AUTHOR]

Air cooling is the traditional solution to chill servers in data centers. However, the continuous increase in global data center energy consumption combined with the increase of the racks' power dissipation calls for the use of more efficient alternatives. Immersion cooling is one such alternative. In this paper, we quantitatively examine and compare air cooling and immersion cooling solutions. The examined characteristics include power usage efficiency (PUE), computing and power density, cost, and maintenance overheads. A direct comparison shows a reduction of about 50% in energy consumption and a reduction of about two-thirds of the occupied space, by using immersion cooling. In addition, the higher heat capacity of used liquids in immersion cooling compared to air allows for much higher rack power densities. Moreover, immersion cooling requires less capital and operational expenditures. However, challenging maintenance procedures together with the increased number of IT failures are the main downsides. By selecting immersion cooling, cloud providers must trade-off the decrease in energy and cost and the increase in power density with its higher maintenance and reliability concerns. Finally, we argue that retrofitting an air-cooled data center with immersion cooling will result in high costs and is generally not recommended. [ABSTRACT FROM AUTHOR]

Big data frameworks such as Storm, Spark and Hadoop are widely deployed in commercial and research applications, the energy consumption of cloud data centers that support big data processing platforms is becoming more and more prominent. However, job scheduling is a complex problem in the presence of various service level agreement (SLA) goals, such as cost reduction and job performance improvement. The highly heterogeneous nature of clusters and the variability of resource requirements acrossworkloads make energy-efficient scheduling on big data platforms extremely complex under SLA constraints. Existing performance-based models and heuristic scheduling methods rely excessively on historical data and are difficult to optimize or modify for changes in load and clusters. In this paper, we construct an energy consumption model based on resource utilization and a reinforcement learning model for energy-efficient scheduling under SLA constraints for Spark clusters, and design two Deep Reinforcement Learning (DRL) algorithms. The cluster scheduler designed and implemented based on this model can automatically capture different load characteristics and inherent cluster characteristics, find the appropriate executor creation policy for resource allocation, and reduce cluster energy consumption under the constraint of job execution time. Experimental results show that the DRL scheduler proposed in this paper saves a maximum energy of about 33% under different load characteristics. [ABSTRACT FROM AUTHOR]

Edge computing aims to make internet-based services and remote computing power close to the user by placing information technology (IT) infrastructure at the network edges. This proximity provides data centers with low-latency and context-aware services. Edge computing power consumption is mainly caused by data centers, network equipment, and user equipment. With edge computing (EC), energy management platforms for residential, industrial, and commercial sectors are built. Energy efficiency is considered to be one of the key aspects of edge power constraints. This paper provides the state of the art of power consumption and energy management for edge computing, the computation off-loading methods, and more important highlights the power efficiency of edge computing systems. Furthermore, renewable energy and related concepts will also be explored and presented since no human participation is required in replacing or recharging batteries when using such energy sources. Based on such study, a recommendation is to develop a dynamic system for energy management in real-time with the assessment of local renewable energy so that the system be reliable with minimum power consumption. Also, regarding energy management, we recommend providing backup energy sources (or using more than one energy source) or (a hybrid technique). [ABSTRACT FROM AUTHOR]

Data Centres serve as the foundation for digital technologies in the energy sector, enabling advanced analytics, optimization, and automation. However, their rapid growth can exert a substantial influence on the environment due to their energy consumption, water utilization, and production of electronic waste. This research begins with an energy overview of the setup and operations of data centres, highlighting their key components and infrastructure, and emphasizing their crucial role in managing energy resources and driving the energy sector's digital technologies. Building upon this understanding, a holistic framework is proposed to tackle energy sustainability concerns in data centres, with a focus on energy-related aspects. The framework places emphasis on three primary sustainability metrics, namely energy efficiency, water consumption, and waste management. It underscores the significance of green building design principles and energy-efficient equipment as crucial constituents of sustainable data centre infrastructure. The framework delineates optimal energy operational best practices encompassing virtualization and consolidation, effective cooling tactics, and energy management and monitoring, all aimed at reducing energy consumption and enhancing energy performance. Furthermore, the framework emphasizes the significance of incorporating energy-related sustainability metrics into decision-making procedures and adhering to regulatory standards for energy efficiency. Through adherence to this framework, data centres' environmental impact can be mitigated and a positive contribution towards a sustainable future can be made, particularly in the realm of energy conservation and optimization. [ABSTRACT FROM AUTHOR]

Preserving the secrecy in the cloud systems is one of the considerable discussion for the further adoption of clouds. The side-channel attacks could extract the private information of other users that shares the computing resources through virtualization. Also, cloud customers face security risks in the context of load balancing of Virtual Machines (VMs). This paper proposes a multi-objective hierarchical load balancing framework to address this issue by means of resource requirement analysis, security and allocating an optimized number of computing resources to every application. The framework is recognized as Secure and Energy Efficient Dynamic Hierarchical Load Balancing Framework for Cloud Data Centers (SEE-DHLB). The experimental results show that our secure VM placement algorithm provides excellent security guarantees and better performance, and achieves better optimality and scalability than previous solutions. It improves the security by using grouping reliability up to 62.21%. Moreover, the model minimizes the power consumption as well as resource utilization up to 38.32% and 73.41% respectively over random, sequential, best fit and DHLB VM placement heuristics. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Donghua University (Natural Science Edition) is the property of Journal of Donghua University (Natural Science) Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

VMP (Virtual Machine Placement) is a crucial technology for energy consumption optimization of the cloud data center. Existing works mainly focus on virtual machine consolidation to increase resource utilization and reduce computing energy consumption. However, existing studies usually ignore the thermal effect that an intensive workload on IT (Information Technology) equipment can raise energy consumption by cooling systems and generate hotspots. In addition, an excessive number of virtual machine migrations increases migration costs and risks violating the SLA (Service Level Agreement) signed with users. In this paper, we present a comprehensive system model and formulate the problem as a constrained multi-objective optimization. We propose a novel thermal-aware VMP strategy to solve the problem by jointly considering virtual machines' migration cost, energy consumption, and heat recirculation around server racks. Our strategy makes placement decisions using MOPFGA (Multi-objective algorithm based on Pathfinder Algorithm and Genetic Algorithm) that combines classic MOPFA and GA enhanced by OBL (Opposition Based Learning) for fast convergence and avoidance of local optimum. Extensive experiments based on CloudSim using real data center workload data from PlanetLab show that our algorithm overcomes the defects of the MOPFA (multi-objective pathfinder algorithm) and GA (genetic algorithm) and significantly improves the overall efficiency of a data center. Compared with several state-of-the-art algorithms, MOPFGA on average reduces virtual machine migrations by 77.52%, increases CRAC (Computer Room Air Conditioner) supply temperature by 1.24%, and reduces cooling energy consumption by 24.78% and computational energy consumption by 23.62%. [ABSTRACT FROM AUTHOR]

Summary: Astra, deployed in 2018, was the first petascale supercomputer to utilize processors based on the ARM instruction set. The system was also the first under Sandia's Vanguard program which seeks to provide an evaluation vehicle for novel technologies that with refinement could be utilized in demanding, large‐scale HPC environments. In addition to ARM, several other important first‐of‐a‐kind developments were used in the machine, including new approaches to cooling the datacenter and machine. This article documents our experiences building a power measurement and control infrastructure for Astra. While this is often beyond the control of users today, the accurate measurement, cataloging, and evaluation of power, as our experiences show, is critical to the successful deployment of a large‐scale platform. While such systems exist in part for other architectures, Astra required new development to support the novel Marvell ThunderX2 processor used in compute nodes. In addition to documenting the measurement of power during system bring up and for subsequent on‐going routine use, we present results associated with controlling the power usage of the processor, an area which is becoming of progressively greater interest as data centers and supercomputing sites look to improve compute/energy efficiency and find additional sources for full system optimization. [ABSTRACT FROM AUTHOR]

The evolution of cloud computing results in the development of numerous huge data-centers. These data-centers use large quantities of electrical energy, which in turn results in high operating cost and high emissions of CO 2 . The grounds for this excessive usage of energy is the inefficient usage of data-center resources (hosts). The resources in the data-center can be in either peak or idle or sleep state. It has been experimentally proven that hosts in the idle state consumes more energy than hosts in sleep state. Through an efficient and optimal VM placement strategy, an energy efficient resource utilization can be achieved, thereby reducing the number of idle hosts in the data-center. This paper introduces two energy efficient VM placement algorithms based on bin packing heuristics considering the physical machine's energy efficiency, Energy Efficient VM Placement (EEVMP) and Modified Energy Efficient VM Placement (MEEVMP), that can reduce the overall energy usage in the data-center. The EEVMP algorithm when compared with the default VM placement algorithm Power-Aware Best-Fit Decreasing algorithm (PABFD) of CloudSim, it reduces the energy consumption by 53%, average SLA violation by 3.5% and number of VM migrations by 64.47%. Further, we have performed MEEVMP algorithm where we achieve a reduction in energy consumption by 54.24%, average SLA violation by 4.39% and number of VM migrations by 67.713 % as compared to PABFD. [ABSTRACT FROM AUTHOR]

Massive MIMO systems can support a large number of Internet of Things (IoT) devices, even if the number of IoT devices exceeds the number of service antennas in a single base station (BS) located at the data center. In order to improve the performance of Massive MIMO with massive IoT connectivity in a BS, simple scheduling and power control schemes can be of great help, but typically, they require high power consumption in the situation of serious shadow fading. In this paper, we try to improve the performance of Massive MIMO with massive IoT connectivity by using the dropping technique that drops the IoT devices that require high power consumption. Several scheduling and power control schemes have been proposed to increase the spectral efficiency (SE) and the energy efficiency (EE) of Massive MIMO systems. By the combination of these schemes with the dropping technique, we show that the performance can be even further increased under some circumstances. There is a dropping coefficient factor (DCF) to determine the IoT devices that should be dropped. This technique gives more benefits to the power control schemes that require higher power consumption. Simulation results and relevant analyses are provided to verify the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]

Deploying data centers in the waters near coastal cities can greatly reduce the distance between data and users, not only eliminating the need to occupy land resources, but also saving energy consumption, which is a completely green and sustainable data center solution. Under the background of resource conservation and green development, this paper puts forward the project of undersea data center heat dissipation. Through the establishment of multiple linear regression model, the influence of tidal and seasonal changes on the heat dissipation of undersea data center is analyzed. Finally, it is concluded that the seasonal changes have the greatest impact on the heat dissipation of the undersea data center container. In the future, the placement strategy of data center and the methods to improve the heat dissipation efficiency will be further discussed. [ABSTRACT FROM AUTHOR]

Featured Application: This study develops a model for a chip-level two-phase cooling system in data centers and employs simulation to investigate its operational characteristics and performance. These findings offer valuable insights for practical implementation. As a powerful solution for heat dissipation in data centers, chip-level cooling continues to capture escalating attention in research and application domains. To accurately analyze system performance, identify potential avenues for system optimization, and inform future practical applications, we developed a steady-state, one-dimensional mathematical model for a novel pump-driven chip-level two-phase cooling system (PCTCS). This model was constructed based on our previous study and was confirmed against existing experimental data. Our simulations scrutinized PCTCS performance under default conditions and investigated the effects of key parameters, such as refrigerant type, condenser vertical positioning, and cooling water temperature. Results showed that the system could manage an 80 W power output from each CPU while maintaining CPU temperatures around 79 °C at a cooling water temperature of 45 °C. We discovered the choice of refrigerant had a significant impact on performance, with R32 outperforming R134a and R113. While the vertical position of the condenser influenced the PCTCS's internal parameters, its overall impact on system performance was negligible. Moreover, provided the chip temperature remained within a safe range, our study found that increasing the cooling water temperature improved the energy efficiency ratio of the refrigerant pump and reduced the temperature difference between the chips and the cold source. [ABSTRACT FROM AUTHOR]

Virtual machine (VM) consolidation is an effective way to improve resource utilization and reduce energy consumption in cloud data centers. Most existing studies have considered VM consolidation as a bin-packing problem, but the current schemes commonly ignore the long-term relationship between VMs and hosts. In addition, there is a lack of long-term consideration for resource optimization in the VM consolidation, which results in unnecessary VM migration and increased energy consumption. To address these limitations, a VM consolidation method based on multi-step prediction and affinity-aware technique for energy-efficient cloud data centers (MPaAFVMC) is proposed. The proposed method uses an improved linear regression prediction algorithm to predict the next-moment resource utilization of hosts and VMs, and obtains the stage demand of resources in the future period through multi-step prediction, which is realized by iterative prediction. Then, based on the multi-step prediction, an affinity model between the VM and host is designed using the first-order correlation coefficient and Euclidean distance. During the VM consolidation, the affinity value is used to select the migration VM and placement host. The proposed method is compared with the existing consolidation algorithms on the PlanetLab and Google cluster real workload data using the CloudSim simulation platform. Experimental results show that the proposed method can achieve significant improvement in reducing energy consumption, VM migration costs, and service level agreement (SLA) violations. [ABSTRACT FROM AUTHOR]

The Internet of Things (IoT) has induced many advances in the modern world, thus always arousing great interest from the scientific community. Due to a large number of connected devices, this paradigm has put into circulation an enormous data quantity to be processed and offloaded while respecting latency and energy constraints that Central Cloud alone cannot meet. Hence, Fog Computing has come to fill these gaps by providing computing, management, and storage resources via small‐distributed data centres located at the network edge. The majority of previous research on centralised clustering in an IoT environment did not consider both residual energy and the location of the IoT devices, as well as the signalling communication frequency, to solve an issue of extreme energy consumption during data exchange between IoT devices and Fog entities. Thus, the objective of this study is to find solutions taking into account these criteria to guarantee the Fog system's energy efficiency while coping with the energy consumption increase related to the handling of massive data volume. Indeed, the proposed study presents a novel approach based on Fog‐IoT architecture to ensure intelligent energy management during communication and offloaded task processing in IoT applications. The simulation results show its effectiveness. [ABSTRACT FROM AUTHOR]

With the rapid growth of cloud computing services, the high energy consumption of cloud data centers has become a critical concern of the cloud computing society. While virtual machine (VM) consolidation is often used to reduce energy consumption, excessive VM consolidation may lead to local hot spots and increase the risk of equipment failure. One possible solution to this problem is to utilize thermal-aware scheduling, but existing approaches have trouble realizing the balance between SLA and energy consumption. This paper proposes a novel method to manage cloud data center resources based on thermal management (TM-VMC), which optimizes total energy consumption and proactively prevents hot spots from a global perspective. Its VM consolidation process includes four phases where the VMs scheduler uses an improved ant colony algorithm (UACO) to find appropriate target hosts for VMs based on server temperature and utilization status obtained in real-time. Experimental results show that the TM-VMC approach can proactively avoid data center hot spots and significantly reduce energy consumption while maintaining low Service Level Agreement (SLA) violation rates compared to existing mainstream VM consolidation algorithms with workloads from real-world data centers. [ABSTRACT FROM AUTHOR]

The rapid development of internet of things (IoT) gadgets and the increase in the rate of sending requests from these devices to cloud data centers resulted in congestion and consequently service provisioning delays in the cloud data centers. Accordingly, fog computing emerged as a new computing model to address this challenge. In fogging, services are provisioned at the edge of the network using devices with computing and storage capabilities, which are located through the way to connect IoT devices to cloud data centers. Fog computing aims to alleviate the computing load in data centers and cut the delay of requests down, notably real-time and delay-sensitive requests. To achieve these goals, vitally important challenges such as scheduling requests, balancing the load, and reducing energy consumption, which affects performance and reliability in the edge-fog-cloud computing architecture, should be considered into account. In this paper, a reinforcement learning fog scheduling algorithm is proposed to address these challenges. The experimental results indicate that the proposed algorithm raises the load balance and diminishes the response time compared to the existing scheduling algorithms. Additionally, the proposed algorithm outperforms other approaches in terms of the number of used devices. [ABSTRACT FROM AUTHOR]

Cloud computing is a commercial and economic paradigm that has gained traction since 2006 and is presently the most significant technology in IT sector. From the notion of cloud computing to its energy efficiency, cloud has been the subject of much discussion. The energy consumption of data centres alone will rise from 200 TWh in 2016 to 2967 TWh in 2030. The data centres require a lot of power to provide services, which increases CO2 emissions. In this survey paper, software-based technologies that can be used for building green data centers and include power management at individual software level has been discussed. The paper discusses the energy efficiency in containers and problem-solving approaches used for reducing power consumption in data centers. Further, the paper also gives details about the impact of data centers on environment that includes the e-waste and the various standards opted by different countries for giving rating to the data centers. This article goes beyond just demonstrating new green cloud computing possibilities. Instead, it focuses the attention and resources of academia and society on a critical issue: long-term technological advancement. The article covers the new technologies that can be applied at the individual software level that includes techniques applied at virtualization level, operating system level and application level. It clearly defines different measures at each level to reduce the energy consumption that clearly adds value to the current environmental problem of pollution reduction. This article also addresses the difficulties, concerns, and needs that cloud data centres and cloud organisations must grasp, as well as some of the factors and case studies that influence green cloud usage. [ABSTRACT FROM AUTHOR]

As the volume of data keeps growing rapidly, more and more storage devices, servers, and network devices are continuously added into data center networks (DCNs) to store, manage, and analyze the data. The industry experience indicates that, instead of adding a huge number of servers into the DCNs at a time, the DCN can also be expanded gradually by adding a small number of servers from time to time. This paper proposes a new type of dual-centric data center network structure, called GHDC (Generalized Hypercube Data Center network architecture), which is constructed by using commodity switches and multi-port servers. After analyzing the shortest distance between any two vertices, a routing algorithm for GHDC is developed. To achieve incremental scalability, two incomplete GHDC structures are proposed. A small number of servers can be added into the incomplete GHDC structures while their topological properties are maintained. The analysis and experiment results show that GHDC significantly outperform the other DCN structures, such as FatTree, BCube, Platonica, FCell, FSquare, and FRectangle, in terms of the incremental scalability and robustness. The average throughput of GHDC is approximately comparable to that of FatTree, BCube, and FSquare, and is higher than that of Platonica, FCell, and FRectangle by about 130.2%, 17.45% and 25.5%. Compared with the FatTree, BCube, FCell, FRectangle, and FSquare, GHDC reduces the cost by about 68.49%, 78.04%, 10.84%, 22.85%, and 29.55%, and reduces the max energy consumption by about 69.45%, 34.48%, 11.55%, 24.31%, and 29.58%, respectively. The actual energy consumption of GHDC is much lower than that of FatTree, BCube, FCell, FRectangle, and FSquare, and is little higher than that of Platonia. [ABSTRACT FROM AUTHOR]

Cloud remains an active and dominant player in the field of information technology. Hence, to meet the rapidly growing requirement of computational processes and storage resources, the cloud provider deploys efficient data centres globally that comprise thousands of IT servers. Because of tremendous energy and resource utilization, a reliable cloud platform has to be necessarily optimized. Effective load balancing is a great option to overcome these issues. However, loading balancing difficulties, such as increased computational complexity, the chance of losing the client data during task rescheduling, and consuming huge memory of the host, and new VM (Virtual Machine), need appropriate optimization. Hence, the study aims to create a newly developed IG-WA (Inquisitive Genetic–Wolf Optimization) framework that meritoriously detects the optimized virtual machine in an environment. For this purpose, the system utilises the GWO (Grey Wolf Optimization) method with an evolutionary mechanism for achieving a proper compromise between exploitation and exploration, thereby accelerating the convergence and achieving optimized accuracy. Furthermore, the fitness function evaluated with an inquisitive genetic algorithm adds value to the overall efficacy. Performance evaluation brings forward the outperformance of the proposed IGWO system in terms of energy consumption, execution time and cost, makespan, CPU utilization, and memory utilization. Further, the system attains more comprehensive and better results when compared to the state of art methods. [ABSTRACT FROM AUTHOR]

Although the coexistence of ARM and INTEL technologies in green data centres is technically feasible, significant challenges exist that must be addressed. These challenges stem from the differences in instruction sets and power consumption between the two processor architectures. While ARM processors are known for their energy efficiency, INTEL processors tend to consume more power. Consequently, evaluating the performance of hybrid architectures can be a complex task. The contributions of this article consist of (i) a multiformalism-based model of a data centre, providing a natural and convenient approach to the specification process and performance analysis of a realistic scenario and (ii) a review of the performance indices, including the choice of one architecture over another, power consumption, the response time, and request loss, according to different policies. As a result, the model aims to address issues such as system underutilization and the need to estimate the optimal workload balance, thereby providing an effective solution for evaluating the performance of hybrid hardware architectures. [ABSTRACT FROM AUTHOR]

With the rapid development of cloud computing, there are more and more large-scale data centers, which makes the energy management of data centers more complex. In order to achieve better energy-saving effect, it is necessary to solve the problems of concurrent management and interdependence of IT, refrigeration, storage, and network equipment. Reinforcement learning learns by interacting with the environment, which is a good way to realize the independent management of the data center. In this paper, a overall energy consumption method for data center based on deep reinforcement learning is proposed to achieve collaborative energy saving of data center task scheduling and refrigeration equipment. A new multi-agent architecture is proposed to separate the training process from the execution process, simplify the interaction process during system operation and improve the operation effect. In the deep learning stage, a hybrid deep Q network algorithm is proposed to optimize the joint action value function of the data center and obtain the optimal strategy. Experiments show that compared with other reinforcement learning methods, our method can not only reduce the energy consumption of the data center, but also reduce the frequency of hot spots. [ABSTRACT FROM AUTHOR]

Cloud data centers consume high volume of energy for processing and switching the servers among different modes. Virtual Machine (VM) migration enhances the performance of cloud servers in terms of energy efficiency, internal failures and availability. On the other end, energy utilization can be minimized by decreasing the number of active, underutilized sources which conversely reduces the dependability of the system. In VM migration process, the VMs are migrated from underutilized physical resources to other resources to minimize energy utilization and optimize the operations. In this view, the current study develops an Improved Metaheuristic Based Failure Prediction with Virtual Machine Migration Optimization (IMFP-VMMO) model in cloud environment. The major intention of the proposed IMFP-VMMO model is to reduce energy utilization with maximum performance in terms of failure prediction. To accomplish this, IMFPVMMO model employs Gradient Boosting Decision Tree (GBDT) classification model at initial stage for effectual prediction of VM failures. At the same time, VMs are optimally migrated using Quasi-Oppositional Artificial Fish Swarm Algorithm (QO-AFSA) which in turn reduces the energy consumption. The performance of the proposed IMFP-VMMO technique was validated and the results established the enhanced performance of the proposed model. The comparative study outcomes confirmed the better performance of the proposed IMFP-VMMO model over recent approaches. [ABSTRACT FROM AUTHOR]

Summary: To meet the ever‐increasing requirements of the applications, cloud service providers have further built and managed multiple cloud data centers in multiple regions across geographies with many physical machines (PMs). However, most of the existing resource allocation algorithms are developed for a single cloud data center, which normally cannot efficiently handle the load burst occasions where a single cloud data center may not be enough to satisfy the demands burst of applications. Therefore, it is necessary to consider how to efficiently manage multiple cloud data centers while meeting application requirements and reducing energy consumption. This paper first systematically analyzes multiple cloud data centers and energy consumption models. Then, an energy‐efficient method of Resource Allocation based on Request Prediction in multiple cloud data centers (RARP) is proposed. The RARP method constructs a resource allocation framework based on request prediction in multiple cloud data centers, which anticipates the application request volume in advance. At the same time, the RARP method allocates VMs and PMs based on the principle of minimum remaining resources available to achieve minimum usage of PMs, thus minimizing energy consumption to complete application requests. Extensive experiments are conducted on the proposed RARP method through the simulation platform CloudSim. Finally, the experimental test results show that the accuracy of request detection and the energy consumption of cloud data centers are significantly better than those of the comparison algorithms. [ABSTRACT FROM AUTHOR]

The primary aim of Virtual Machine Placement (VMP) is the mapping of Virtual Machines (VMs) to Physical Machines (PMs), such that the PMs may be utilized to their maximum efficiency, where the already active VMs are not to be interrupted. It provides a list of live VM migrations that must be accomplished to get the optimum solution and reduces energy consumption significantly. The inefficient VMP leads to wastage of resources and excessive energy consumption and increases the overall operational cost of the data center. A Metaheuristic Virtual Machine Placement Framework towards the Power Efficiency of Sustainable Cloud Environment (MV-PESC) approach is suggested to address the issues mentioned above. An Extended Flower Pollination Optimization algorithm is suggested, which combines the concept of the Random Fit algorithm and the Flower Pollination Optimization algorithm. The proposed work's performance is evaluated using actual workload traces of the benchmark Google Cluster Data set. The obtained results are compared with various state-of-the-art and demonstrate a notable reduction in power consumption, the number of active PMs, and execution time up to 64.89%, 35%, and 21.12%, respectively. [ABSTRACT FROM AUTHOR]

Scheduling independent tasks on a parallel platform is a widely-studied problem, in particular when the goal is to minimize the total execution time, or makespan (P | | C max problem in Graham's notations). Also, many applications do not consist of sequential tasks, but rather parallel tasks, either rigid, with a fixed degree of parallelism, or moldable, with a variable degree of parallelism (i.e., for which we can decide at the execution on how many processors they are executed). Furthermore, since the energy consumption of data centers is a growing concern, both from an environmental and economical point of view, minimizing the energy consumption of a schedule is a main challenge to be addressed. One can then decide, for each task, on how many processors it is executed, and at which speed the processors are operated, with the goal to minimize the total energy consumption. We further focus on co-schedules, where tasks are partitioned into shelves, and we prove that the problem of minimizing the energy consumption remains NP-complete when static energy is consumed during the whole duration of the application. We are however able to provide an optimal algorithm for the schedule within one shelf, i.e., for a set of tasks that start at the same time. Several approximation results are derived, both with discrete and continuous speed models, and extensive simulations are performed to show the performance of the proposed algorithms. • A model for a theoretical analysis of the energy consumption of a schedule for moldable and rigid tasks. • Most presented scheduling problems are NP-complete. • There exist approximation algorithms for the presented problems (from 1.59 to 3 depending on the problem). • An experimental study of the trade-off between the time complexity of the scheduler and the energy consumed by the schedule. [ABSTRACT FROM AUTHOR]

Energy is a considerable portion of the cost of a cloud data center. In addition to energy, carbon emission tax imposes another cost on data centers, which have different policies in different cities around the world. Most of the cloud data centers are geographically distributed, which can have a huge advantage in reducing such costs. In addition, in recent years, cloud federation, in which multiple cloud providers share their IT infrastructures voluntarily, could play a crucial role in minimizing the energy consumption of cloud data centers. On the other hand, improper VM placement results frequent VM migration, constant turning off/on physical machines, service quality degradation and energy consumption increase. To tackle these weaknesses, we propose a multi-objective algorithm, Called OUR-ACS, to minimize data centers' energy consumption, carbon emission, and the total expenses (energy cost + carbon tax) in a federated environment considering both initial VM placement and VM consolidation approaches. We evaluate the efficiency of our proposed algorithm by using the ClousSim Plus simulator toolkit using real-world datasets. Compared to the competing algorithms, our simulation results indicate that our proposed algorithm could reduce the total energy consumption, carbon emission, and the total costs of multiple cloud data centers by an average of 37.6%, 41%, and 25%, respectively, in a federated environment. • We propose a novel multi-objective cloud federation algorithm considering to minimize three objectives. • We have identified a new problem in VM migration called Migration lock-in status. • We employ new heuristics to make a tradeoff between servers' power consumption and their resource utilization simultaneously. • We conduct a comprehensive simulation under an IaaS cloud infrastructure using a real-world datasets. [ABSTRACT FROM AUTHOR]

Active adjustment of the airflow organization in data centers (DC) has been increasingly applied due to its superior adjustment performance. But for now, the main focus is on the airflow distribution optimization in the horizontal direction, while few research has been conducted to investigate the additional energy consumption of active method. This paper introduced the jet-induced ventilation into under-floor air distribution (UFAD), then the coupling air supply system (CASS) was established. Taking the CASS data center as an example, this paper focuses on the impact of the active adjustment method on both airflow organization and energy consumption of the DC, and analyzes the energy consumption of the system while meeting the security operations of the thermal environment. The results showed that the incorporation of jet-induced ventilation effectively improved the airflow distribution uniformity, while the active adjustment of the airflow organization in the DC has little effect on the overall energy consumption. On the premise of meeting the demand of thermal environment, the energy consumption of the CRAC (Computer room air conditioning) units in the CASS is reduced and the change of the overall energy consumption is small, while the total energy consumption increased with the increase of airflow uniformity. [ABSTRACT FROM AUTHOR]