High Availability

This article presents a strategic framework for implementing master data management excellence within enterprise organizations, with particular emphasis on manufacturing and distribution environments. The article explores the critical role of master data as the foundational information asset that transcends departmental boundaries and serves as the authoritative source for enterprise-wide business processes. Through systematic analysis of governance frameworks, data cleansing techniques, and quality assurance methodologies, this article establishes six guiding principles that form the foundation of enterprise data strategy maturity: governing organization, process standardization, data quality, data as an asset, data source rationalization, and single source of truth. The article reveals that organizations with mature master data management practices achieve substantially higher operational efficiency and improved customer satisfaction scores compared to their counterparts with fragmented data architectures. The article emphasizes the journey-based nature of master data maturity evolution, proposing a progressive development approach that builds capabilities incrementally while delivering measurable business value at each maturity stage. The article provides actionable recommendations for implementing sustainable governance frameworks, establishing comprehensive data stewardship programs, and integrating advanced data cleansing techniques within broader master data management ecosystems. The findings demonstrate that successful master data management requires holistic approaches that integrate governance frameworks, technology infrastructure, and organizational change management initiatives to create lasting competitive advantages through enhanced data capabilities.

Com a expansão das organizações e de suas redes computacionais, sua alta disponibilidade é um requisito chave. Até mesmo curtos períodos de inatividade de uma rede podem gerar perdas de produtividade. Diante disso, o presente trabalho apresenta uma proposta de otimização do tráfego da Rede da Universidade Federal de Lavras, através da implantação de redundâncias e a posterior implantação da técnica de Spanning Tree Protocol (STP). Os testes realizados em laboratório contribuíram para avaliar a viabilidade da utilização em campo desta tecnologia e mostraram que o tempo gasto pelo STP para restabelecer os serviços de rede é insignificante se comparado ao tempo que geralmente a Rede Ufla fica indisponível após a ocorrência de uma falha.

Disasters are an inevitable part or our lives. Much of the work and tools used currently are intended to address the first stage to a disaster which is response. Work related to a later stage, long-term disaster recovery, is scarce and an attempt to offer a business case approach to the implementation of a web-based tool for this stage is discussed in this work. Stages to develop the tool, costs, and benefits are explained as well as some parts of the National Disaster Recovery Framework.

Checkpoint-recovery based virtual machine (VM) replication is an attractive technique for accommodating VM installations with high-availability. It provides seamless failover for the entire software stack executed in the VM regardless the application or the underlying operating system (OS), it runs on commodity hardware, and it is inherently capable of dealing with shared memory nondeterminism of symmetric multiprocessing (SMP) configurations. There have been several studies aiming at alleviating the overhead of replication, however, due to consistency requirements, network performance of the basic replication mechanism remains extremely poor. In this paper we revisit the replication protocol and extend it with speculative communication. Speculative communication silently acknowledges TCP packets of the VM, enabling the guest's TCP stack to progress with transmission without exposing the messages to the clients before the corresponding execution state is checkpointed to the backup host. Furthermore, we propose replication aware congestion control, an extension to the guest's TCP stack that aggressively fills up the VMM's replication buffer so that speculative packets can be backed up and released earlier to the clients. We observe up to an order of magnitude improvement in bulk data transfer with speculative communication, and close to native VM network performance when replication awareness is enabled in the guest OS. We provide results of micro-, as well as application-level benchmarks.

High availability and reliability are among the most desirable features of control systems in modern High-Energy Physics (HEP) and other big-scale scientific experiments. One of the recent developments that has influenced this field was the emergence of the Advanced Telecommunications Computing Architecture (ATCA). Designed for the telecommunications industry it has been successfully applied in other domains such as accelerator control systems. A good example is the application of ATCA standard for the design of Low Level RF (LLRF) control system for the X-Ray Free Electron Laser (XFEL) being developed in Deutsches Elektronen Synchrotron (DESY). Reliability and availability requirements for such a device play a crucial role among other parameters. Thus, the ATCA standard, with fivenines availability, is considered one of the best candidates for this system. This article focuses on the central management unit of every ATCA board, namely the Intelligent Platform Management Controller (IPMC), developed for the LLRF ATCA Carrier Board (CB). It also argues that it is possible to create a fully functional IPMC using base specifications only which is a much more economical solution than acquiring such products from various vendors dealing with ATCA-related products. The solution presented here fully complies with all the most recent revisions of specifications that are required for an ATCA board to properly operate in an ATCA shelf, communicate with the redundant Shelf Manager (ShM) and host Advanced Mezzanine Cards (AMCs). Full Electronic-Keying (EK) functionality is present on the LLRF CB supporting such protocols as PCI Express (PCIe), Gigabit Ethernet (GbE) and proprietary Low Latency Links (LLL) making it possible to route connections between all the boards in the system. The IPMC solution presented here is mainly hardware independent as proper code organization allowed to separate low-level device drivers and high-level application logic dealing with the ATCA standard, which makes it portable to new carrier board designs.

The evolving dynamics of global finance necessitate the adoption of advanced digital platforms to streamline operations, enhance data-driven decision-making, and ensure regulatory compliance. SAP BW/4HANA, as a next-generation data warehouse solution, offers powerful analytics and real-time data processing capabilities tailored for financial management. This paper explores the implementation of SAP BW/4HANA in financial operations, assessing its impact on business process efficiency, reporting accuracy, and strategic planning. Through a structured analysis of system architecture, data integration strategies, and business use cases, the paper demonstrates how SAP BW/4HANA improves financial consolidation, reduces latency in reporting, and enhances overall financial transparency. Furthermore, the paper provides quantitative and visual evidence from enterprise implementations to underscore the tangible improvements in financial process optimization.

In today's world, where technology plays a crucial role in development, education is also benefiting from advancements in network infrastructure and virtualized services. Virtualization technology and highavailability (HA) infrastructures usage can transform how educational institutions manage and deliver their services. This is especially important for learning environments that require continuous access to critical systems such as data servers, online learning platforms, and student resources. Network and server administrators in educational institutions must ensure the availability and security of their systems. Building high-availability infrastructures enables the creation of more secure and stable environments, ensuring uninterrupted access to essential resources for students and educators. This paper addresses the use of virtualization technology in managing high-availability services using open-source tools. Educational services can be hosted on virtual machines that are automatically migrated between physical nodes of a cluster system in case of a network failure, ensuring a seamless experience for users. The project utilizes the open-source Heartbeat program to enable real-time migration of virtual machines between physical nodes in a cluster. A solution and algorithm (Perf+) will be developed to improve CPU performance and memory and reduce downtime during migration. The solution will be tested in an experimental HA system, measuring the impact of migration on performance. This approach helps educational institutions adopt innovative technologies to enhance the quality of education, ensuring continuous and reliable access to their services.

The integration of Artificial Intelligence (AI) and Machine Learning (ML) into SAP platforms is revolutionizing enterprise resource planning by driving automation, predictive insights, and intelligent decision-making. This paper explores the transformative potential of AI/ML in SAP systems such as S/4HANA, SAP BTP, and SAP Leonardo. It outlines how organizations can leverage AI-driven analytics, intelligent automation, and real-time data processing to enhance operational efficiency and deliver measurable business value. By presenting a comprehensive literature review, technical working principles, and practical use cases, this study highlights key enablers and challenges in AI/ML adoption within SAP environments. The paper concludes with forwardlooking enhancements and strategies for future-proofing enterprise systems through intelligent technologies.

The rapid digital transformation in the financial sector has created an urgent demand for deploying machine learning and AI models at scale in a secure, efficient, and scalable manner. Traditional model deployment techniques often lack the flexibility, automation, and scalability needed for real-time financial applications, especially when dealing with fluctuating workloads, regulatory constraints, and stringent latency requirements. Cloud-native technologies-cantered around containerization, orchestration, and microservicesoffer a robust paradigm for deploying models that power personalized banking, fraud detection, risk modeling, and algorithmic trading. This paper presents a comprehensive framework for cloudnative model deployment tailored specifically for financial applications. The proposed system architecture leverages container-based packaging (Docker), orchestration tools (Kubernetes), and model serving platforms such as Seldon Core and KFServing to enable scalable, versioned, and monitored model lifecycles. The framework integrates CI/CD pipelines with MLOps principles, ensuring continuous delivery and retraining in regulated environments. In addition, it supports hybrid cloud strategies, offering seamless integration with APIs, financial data warehouses, and regulatory monitoring tools. Through experiments and performance evaluations, the cloudnative deployment pipeline was validated on various financial use cases, including credit scoring, anomaly detection, and investment forecasting. Metrics such as response latency, system scalability, and fault tolerance were measured and benchmarked against traditional deployment architectures. The results demonstrated significant improvements in deployment velocity, scalability, and operational transparency, making the approach highly suitable for modern FinTech ecosystems.

The integration of cloud-based solutions into enterprise environments has transformed the way organizations manage business processes and foster collaboration. SAP Cloud Solutions, particularly through platforms like SAP Business Technology Platform (SAP BTP), SAP S/4HANA Cloud, and SAP Work Zone, offer a comprehensive and scalable approach to Business Process Management (BPM) while enhancing team collaboration across departments and geographies. This paper explores how SAP Cloud Solutions enable streamlined workflows, real-time data integration, and intelligent automation, which collectively contribute to increased agility and efficiency. Through a detailed analysis of core components, architectural frameworks, and real-world use cases, this study highlights the critical role of SAP Cloud in modern digital enterprises. It also discusses potential risks, challenges in adoption, and future innovations that may further drive the effectiveness of cloud-based BPM.

The high availability of electron donors occurring in coastal upwelling ecosystems with marked oxyclines favours chemoautotrophy, in turn leading to high N 2 O and CH 4 cycling associated with aerobic NH + 4 (AAO) and CH 4 oxidation (AMO). This is the case of the highly productive coastal upwelling area off central Chile (36 • S), where we evaluated the importance of total chemolithoautotrophic vs. photoautotrophic production, the specific contributions of AAO and AMO to chemosynthesis and their role in gas cycling. Chemolithoautotrophy was studied at a time-series station during monthly (2007)(2008)(2009) and seasonal cruises

The world around us is moving at an extremely fast pace than ever before and Information technology plays a pivotal role in driving this momentum forward. With its growth and innovations, the biggest challenge information technology brings is its Security, which is commonly known as Cyber Security. From Small Organizations to massive government infrastructures, Everyone takes exceptional measures to prevent cybercrimes So that businesses can continue to Operate Smoothly. This paper mainly focuses on Business Continuity & Disaster Recovery after a Cyber Attack. It also explains the latest Cyber Security Techniques, trend changes & Threats.

The increasing reliance on data-driven decision-making in businesses and
organizations has made database migration a critical aspect of modern IT infrastructures.
Cross-platform database migration, while vital for evolving technological landscapes, comes
with a host of challenges. This paper presents an in-depth study on automated cross-platform
database migration and high availability implementation. The research focuses on the
automation of the migration process, which allows for the seamless transition of databases
between different platforms, such as from on-premises systems to cloud platforms. It explores
the implementation of high availability (HA) mechanisms to ensure the uninterrupted
operation of databases during migration, reducing downtime and minimizing the risks of data
loss. The study investigates the various tools and technologies employed in the automated
migration process, including real-time replication, disaster recovery, and failover systems.
Through comprehensive case studies, we demonstrate how automated tools improve the
efficiency and reliability of migration while maintaining system availability. A significant
portion of the paper discusses the underlying technical considerations of setting up automated
migration environments, such as ensuring data integrity, schema compatibility, and minimal
service disruption. This research aims to provide organizations with a framework for
understanding the key challenges and best practices associated with cross-platform database
migration and high availability. It also offers recommendations for leveraging automation to
enhance operational efficiency. The results underscore the importance of effective migration
planning and choosing the right set of tools to ensure success.

Linear gas stopping cells have been used successfully at NSCL to slow down ions produced by projectile fragmentation from the 100 MeV/u to the keV energy range. These 'stopped beams' have first been used for low-energy high precision experiments and more recently for NSCLs re-accelerator ReA. A gas-filled reverse cyclotron is currently under construction by the NSCL to complement the existing stopping cells: Due to its extended stopping length, efficient stopping and fast extraction is expected even for light and mediummass ions, which are difficult to thermalize in linear gas cells. The device is based on a 2.6 T maximum-field cyclotron-type magnet to confine the injected beam while it is slowed down in ≈100 mbar of LN 2 -temperature helium gas. Once thermalized, the beam will be transported to the center of the device by a traveling-wave RF-carpet system, extracted along the symmetry axis with an ion conveyor and miniature RF-carpets, and accelerated to a few tens of keV of energy for delivery to the users.

In the paper modern concepts of radio communication trunking-dispatch systems for special applications are presented. Basic standards of TETRA, DMR, and cdma2000 are mentioned. The aim of the paper is to present innovative trunking solutions based on the LTE system working both in FDD and TDD mode. The architecture of LTE trunked radio is shown as well as new services possible to implementation are described. The way of TETRA and LTE integration is characterized.

Due to the low cost and effectiveness of sulphadimidine against a wide variety of animal diseases, it is still being widely used in veterinary medicine. The present study was carried out to determine the effect of age on the pharmacokinetics of sulphadimidine in West African Dwarf (WAD) goats following intramuscular route of administration. Eight (8) WAD goats separated into two groups of four animals consisting of two males and two female goats each were used. Sulphadimdine sodium was administered at a dose of 100 mg/kg body weight. The goats in group one (3 months of age) and goats in group two (2 years old) were administered the drug on the right gluteal muscle. The pharmacokinetic parameters in the 3 months old WAD goats such as the maximum concentration (Cmax) (88.52±6.07), elimination half life (T1/2β) (3.79±0.29 h), volume of distribution (Vd) (4.55±0.46 L/kg), total body clearance (Cl) (0.77±0.09 L/kg/h) and mean residence time (MRT) (4.57 ± 0.48 h), were significantly (p<0.05) lower in comparison with Cmax (103. 59 ±7.56), T1/2β (4.90 h), Vd (13.03±1.58 L/kg), Cl (1.91±0.26 L/kg/h) and MRT (7.10±0.73 h) of the 2 years old WAD goats. The pharmacokinetic parameters of sulphadimidine in the 3 months old WAD goats were significantly different from that of the 2 years old WAD goats. This may be due to the difference in their body fat and water content.

The convergence of communication networks and the demand for storage and processing capacities for large amounts of information, especially in recent years, has driven requests for everything-as-a-service and has been generating, on an increasing scale, demands for new data center constructions. However, to meet dependability attributes, the design of these infrastructures needs to consider, at least, the system’s availability to be achieved. In this paper, we evaluate the availability of a Tier 1 data center infrastructure, considering the use of blade systems. We use modeling techniques based on reliability block diagrams and stochastic Petri nets to simulate a maintenance policy encompassed at different service levels (SLA). The results show dependability metrics, focusing on the availability and maintenance of these networks. We highlight the most severe difficulties in achieving high availability when there is no component redundancy, and the intervals between maintenance are l...

SAP S/4HANA Cloud Central Finance represent a strategic enabler for enterprises aiming to unify financial operations across fragmented SAP and non-SAP ERP environments. By centralizing financial data and processes within a single, cloud-based SAP S/4HANA instance, organizations can adopt a "Finance First" transformation path delivering immediate values without disrupting existing systems. This approach unlocks enterprise-wide financial visibility, accelerates close and reporting cycles and streamlines landscapes, offering a scalable and cost-effective foundation for full S/4HANA migration. It empowers finance leader with real-time insights, harmonized data, and enhance control to drive agile, data-driven decisions. However, to fully capitalize on these benefits, organizations must address critical challenges, including data harmonization, system integrations, and change management

Version vectors (VV) are used pervasively to track dependencies between replica versions in multi-version distributed storage systems. In these systems, VV tend to have a dual functionality: identify a version and encode causal dependencies. In this paper, we show that by maintaining the identifier of the version separate from the causal past, it is possible to verify causality in constant time (instead of O(n) for VV) and to precisely track causality with information with size bounded by the degree of replication, and not by the number of concurrent writers.

Internet is often used for transaction based applications such as online banking, stock trading, among many others where the service outages are unacceptable. It is important for designers of such applications to analyze how hardware, software and performance related failures affect the quality of service delivered to the users. This paper presents analytical models for evaluating the service availability of web cluster architectures. A composite performance and availability modeling approach is defined considering various causes of service unavailability. In particular, web cluster systems are modeled taking into account: two recovery strategies (client transparent and non client-transparent). Sensitivity analysis results are presented to show their impact on the web service availability. The obtained results are aimed at providing useful guidelines to web designers.

Present basis of knowledge management is the efficient share of information. The challenges that modern industrial processes have to face are multimedia information gathering and system integration, through large investments and adopting new technologies. Driven by a notable commercial interest, wireless networks like GSM or IEEE 802.11 are now the focus of industrial attention, because they provide numerous benefits, such as low cost, fast deployment and the ability to develop new applications. However, wireless nets must satisfy industrial requisites: Scalability, flexibility, high availability, immunity to interference, security and many others that are crucial in hazardous and noisy environments. This paper presents a thorough survey of all this requirements, reviews the existing wireless solutions, and explores possible matching between industry and the current existing wireless standards.

In today's data-intensive business scenario, the integrity and availability of missioncritical systems are of utmost importance. Microsoft SQL Server is a heavily used product by organizations to store and manage critical business information. Accordingly, maintaining uninterrupted data access through strong High Availability (HA) and Disaster Recovery (DR) solutions is crucial to reduce downtime, avoid data loss, and ensure business continuity. This paper discusses the architecture, implementation, and best practices of constructing effective HA and DR plans particularly for SQL Server environments with emphasis on real-time protection of mission-critical applications. The paper discusses the comparative study of native SQL Server features like Always On Availability Groups, Failover Cluster Instances (FCIs), Log Shipping, Database Mirroring, and Backup/Restore approaches. It also addresses how third-party offerings and real-time data replication technologies aid in the optimization of recovery point objectives (RPO) and recovery time objectives (RTO). It looks into cloud DR solutions and hybrid models integration to discover how they can complement on-premises infrastructures with economical, scalable alternatives. In addition, the research discusses real-time HA/DR challenges including network latency, storage replication consistency, application failover compatibility, and the administrative burden in configuring and monitoring HA/DR solutions. Automation of failover processes, round-the-clock monitoring, and performing periodic DR drills to be well-prepared is also of much importance. Using case studies and actual implementations, the paper illustrates how businesses from various industries have been able to achieve near-zero downtime and fractional data loss by implementing sophisticated HA and DR mechanisms. Business size, budget limitations, compliance demands, and system criticality are used as guidelines to make recommendations for selecting the appropriate HA/DR strategy. Finally, this paper provides value to the IT practitioner and system architect by providing a well-defined method for designing, implementing, and managing high availability and disaster recovery plans for SQL Server. Highlighting real-time data protection is to ensure that mission-critical business systems continue to function even if there is hardware failure, cyber-attack, or natural disasters.

In the era of real-time data processing and global operations, ensuring the high availability (HA) of mission-critical databases is a cornerstone of IT infrastructure strategy.[1] SQL Server, a widely adopted relational database management system, is the backbone of numerous enterprise applications. With the increasing demand for uninterrupted services and global data access, traditional high availability configurations-often restricted to a single region or data center-have proven inadequate.[2] As a result, businesses are adopting distributed "Always On" architectures that provide worldwide continuity, using hybrid clouds, regionally dispersed replicas, and smart failovers.[3] "Always On" Availability Groups, which was added in SQL Server 2012, has matured to accommodate multi-region deployment patterns, thereby providing a foundation for globally dispersed systems.[4] By providing synchronization among geographically dispersed replicas, these architectures not only improve availability but also provide read-scale out, disaster recovery (DR) capabilities, and load balancing. Designing, deploying,[6] and maintaining these distributed systems, however, necessitates a thoughtful strategy that involves defined patterns, automation, and monitoring.[7] Such patterns can include hub-and-spoke topologies, quorum models, and geo-distributed listener setups. [8] Terraform, an open-source Infrastructure as Code (IaC) tool developed by HashiCorp, is the key enabler of automation to deploy such sophisticated environments.[9] When used in conjunction with ARM templates and Azure Resource Manager, Terraform enables infrastructure engineers to reproduce patterns for HA configurations across geographic regions with less human error, version

We live in an increasingly interconnected world, with many organizations operating across countries or even continents. To serve their global user base, organizations are replacing their legacy DBMSs with cloud-based systems capable of scaling OLTP workloads to millions of users. CockroachDB is a scalable SQL DBMS that was built from the ground up to support these global OLTP workloads while maintaining high availability and strong consistency. Just like its namesake, CockroachDB is resilient to disasters through replication and automatic recovery mechanisms. This paper presents the design of CockroachDB and its novel transaction model that supports consistent geo-distributed transactions on commodity hardware. We describe how CockroachDB replicates and distributes data to achieve fault tolerance and high performance, as well as how its distributed SQL layer automatically scales with the size of the database cluster while providing the standard SQL interface that users expect. Finally, we present a comprehensive performance evaluation and share a couple of case studies of CockroachDB users. We conclude by describing lessons learned while building CockroachDB over the last five years.

This study, called APEX, is exploring novel concepts for fusion chamber technology that can substantially improve the attractiveness of fusion energy systems. The emphasis of the study is on fundamental understanding and advancing the underlying engineering sciences, integration of the physics and engineering requirements, and enhancing innovation for the chamber technology components surrounding the plasma. The chamber technology goals in APEX include: (1) high power density capability with neutron wall load \ 10 MW/m 2 and surface heat flux \ 2 MW/m 2 , (2) high power conversion efficiency ( \ 40%), (3) high availability, and (4) simple technological and material constraints. Two classes of innovative concepts have emerged that offer great promise and deserve further www.elsevier.com/locate/fusengdes

In today's data-intensive business scenario, the integrity and availability of missioncritical systems are of utmost importance. Microsoft SQL Server is a heavily used product by organizations to store and manage critical business information. Accordingly, maintaining uninterrupted data access through strong High Availability (HA) and Disaster Recovery (DR) solutions is crucial to reduce downtime, avoid data loss, and ensure business continuity. This paper discusses the architecture, implementation, and best practices of constructing effective HA and DR plans particularly for SQL Server environments with emphasis on real-time protection of mission-critical applications. The paper discusses the comparative study of native SQL Server features like Always On Availability Groups, Failover Cluster Instances (FCIs), Log Shipping, Database Mirroring, and Backup/Restore approaches. It also addresses how third-party offerings and real-time data replication technologies aid in the optimization of recovery point objectives (RPO) and recovery time objectives (RTO). It looks into cloud DR solutions and hybrid models integration to discover how they can complement on-premises infrastructures with economical, scalable alternatives. In addition, the research discusses real-time HA/DR challenges including network latency, storage replication consistency, application failover compatibility, and the administrative burden in configuring and monitoring HA/DR solutions. Automation of failover processes, round-the-clock monitoring, and performing periodic DR drills to be well-prepared is also of much importance. Using case studies and actual implementations, the paper illustrates how businesses from various industries have been able to achieve near-zero downtime and fractional data loss by implementing sophisticated HA and DR mechanisms. Business size, budget limitations, compliance demands, and system criticality are used as guidelines to make recommendations for selecting the appropriate HA/DR strategy. Finally, this paper provides value to the IT practitioner and system architect by providing a well-defined method for designing, implementing, and managing high availability and disaster recovery plans for SQL Server. Highlighting real-time data protection is to ensure that mission-critical business systems continue to function even if there is hardware failure, cyber-attack, or natural disasters.

AMOEBA is a research project to build a true distributed operating system using the object model. Under the COST11-ter MANDIS project this work was extended to cover wide-area networks. Besides describing the system, this paper discusses the successive versions in the implementation of its model, and why the changes were made. Its purpose is to prevent ourselves and others from making the same mistakes again, and to illustrate how a distributed operating system grows in sophistication and size. "Those who learn nothing fi'om history are doomed to repeat it" --Santayana For about eight years now, we have been doing research on distributed operating systems, not only behind our desks, but also behind our terminals. The distributed system we are developing is called AMOEBA[l], and it is constantly evolving. It is being developed at the Vrije Universiteit and the Centre for Mathematics and Computer Science (CWI), both in Amsterdam. AMOEBA currently runs on Motorola 68020, National Semiconductor 32032, and MicroVax II processors. Both Ethemet and the Pronet token ring are supported by AMOEBA, and can be connected by a bridge. COST11-ter MANDIS is an international project investigating the management requirements for large international networks of computers. It has adopted the object-model as a framework within which to discuss the management of wide-area distributed systems. To experiment with this, the MANDIS project adopted the Amoeba distributed operating system, extended with a gateway for wide-area communication. Amoeba systems in Holland (Vrije Universiteit, CWI), the U.K. (Harwell Laboratories, Haffield Polytechnic), in Berlin (GMD/FOKUS) and in Norway (University of Troms0) have been connected into a single, transparent distributed system.

Most distributed operating systems constructed to date have lacked a unifying mechanism for naming and protection. In this paper we discuss a system, Amoeba, that uses capabilities for naming and protecting objects. In contrast to traditional, centralized operating systems, in which capabilities are managed by the operating system kernel, in Amoeba all the capabilities are managed directly by user code. To prevent tampering, the capabilities are protected cryptographically. The paper describes a variety of the issues involved, and gives four different ways of dealing with the access rights. This paper describes a scheme in which user processes manipulate capabilities directly in their own address spaces. Except for some very special parts of it, the kernel does not even know that capabilities are in use. To prevent users from forging new capabilities or tampering with existing ones, capabilities are protected cryptographically. This cryptographic protection scheme will first be described in some detail, followed by a discussion of how these capabilities are used in the Amoeba distributed operating system. Amoeba is an object-oriented distributed operating system. Its semantic model is based on having client processes perform operations on objects managed by server processes. Objects are specified by capabilities. Operations are carried out by having processes exchange messages, generally in the form of a request from a client followed later by a reply from a server. The standard message format provides a place for one capability in the header, typically for the object being operated on, but users are free to put other capabilities in the data field as required. The header also contains room for the operation code and some parameters. After making a request, a client blocks until the reply comes in, so the approach can be regarded as a simple remote procedure call mechanism . The system does not use "connections" or virtual circuits or any other long-lived communication structures.

We propose group communication as an efficient mechanism to support fault tolerance. Our approach is based on an efficient reliable broadcast protocol that requires on average only two messages per broadcast. To illustrate our approach we will describe how the task bag model can be made fault-tolerant using group communication.

The Globe Distribution Network (GDN) is an application for the efficient, worldwide distribution of freely redistributable software packages. Distribution is made efficient by encapsulating the software into special distributed objects which efficiently replicate themselves near to the downloading clients. The Globe Distribution Network takes a novel, optimistic approach to stop the illegal distribution of copyrighted and illicit material via the network. Instead of having moderators check the packages at upload time, illegal content is removed and its uploader's access to the network permanently revoked only when the violation is discovered. Other protective measures defend the GDN against internal and external attacks at its availability. By exploiting the replication of the software and using fault-tolerant server software, the Globe Distribution Network achieves high availability. This article describes the design of the GDN and a number of small experiments with its prototype implementation.

We propose OX, a runtime system that uses application-level availability constraints and application topologies discovered on the fly to enhance resilience to infrastructure anomalies for cloud applications. OX allows application owners to specify groups of highly ...

A residual gas fluorescence beam profile monitor at the relativistic heavy ion collider (RHIC) has successfully recorded vertical beam sizes of Au-ion beams from 3.85 to 100 GeV/n during the 2010 beam runs. Although the fluorescence cross section of Au-ion is sufficiently large, the low residual gas in a typical vacuum chamber of <10 -9 torr produces necessary weak fluorescence photons. However, with adequate CCD exposure time, the vertical beam profiles are captured to provide an independent measurement of the RHIC beam size and emittance. This beam diagnostic technique, utilizing the Au-ion beam induced fluorescence from residual gas where hydrogen is still the dominant constituent in nearly all vacuum system, represents a step towards the realization of a truly noninvasive beam monitor for high-energy particle beams.

This article describes the novel stochastic modeling tool OpenSESAME which allows for a quantitative evaluation of fault-tolerant High-Availability systems. The input models are traditional reliability block diagrams (RBD) which can be enriched with inter-component dependencies like failure propagation, failures with a common cause, different redundancy types, and non-dedicated repair. OpenSESAME offers a novel set of graphical diagrams to specify these dependencies. Due to the dependencies, traditional solution methods for RBDs cannot be applied to OpenSESAME models. We therefore present a novel evaluation method, which is based on the automatic generation of several state-based models, which are semantically equivalent to the high-level input model. Alternatively, either stochastic Petri nets or textual models based on a stochastic process algebra can be generated. The state based models are then analyzed using existing solvers for these types of models. Three case studies exemplify the modeling power and usability of OpenSESAME.

To determine the environmental free metal ion activity was a recent hot issue. A method to measure low-level free cupric ion activity in soil solution extracted with 0.01 mol/L KNO, was developed by using cupric ion-selective electrode (ISE) and calibrating with Cu-buffer solution. Three copper buffers including iminodiacetic acid (IDA), ethylenediamine (EN), and glycine (Gly) were compared for calibrating the Cu-ISE curves in the range of free cupric ions (pCu*+) 7-13, The Cu-EN buffer showed the best electrode response and thus was applied as the calibration buffer. The pCu> of 39 contaminated agricultural soils around a copper mine was measured, ranging from 5.03 to 9.20. Most Cu in the soil solutions was found to be complexed with dissolved soil organic matters, averaging 98.1%. The proportion of free Cu2+ ions in the soil solutions decreased with the increasing of solution pH. Soluble Cu and free Cu2+ ions concentrations were analyzed by multiple linear regressions to evaluate the effects of soil properties on metal levels and speciation. The results showed that soil solution pH was the most significant factor influencing pCu" (with RZ value of 0.76), while not important for the soluble Cu concentration.

The interaction between Pb-17Li and water, as a consequence of a localized tube microcrack, has been studied. Two experiments were performed in which a low quantity of steam was injected into the lithium lead. The artificially machined microcracks, simulating a real microcrack in an AISI 316 heat exchanger tube, had a maximum area of 0.003 mm 2. No blockage of the microcrack was observed during the tests. No significant damage was observed on the microcracks geometry, probably because of the short test time. A layer of reaction products having a high melting point was formed around the test section. First analytical results seem to confirm the presence of lithium hydroxide in the reaction products.

Web-based systems include comprehensive interaction between component-based system objects in various situations on a wide-area network-based environment ]. Therefore, Web-based applications are vulnerable to network partitioning failures. A network partitioning splits the network into two or more disjoint parts. Processes of a Web-based application within the same part can communicate with each other, but they cannot communicate with processes of the application located in other parts. In order for the application to be continuously operational, data and processes must be replicated in the network. However, application processes may perform some incompatible operations that can result in inconsistent data during the network partitioning. The challenge is to let the application continue its operations during a network partitioning, yet to reconcile the effects of incompetible operations when the communication is restored ]. The application under our consideration is a Web-based sales system spread across three cities: Melbourne, Sydney and Geelong. Each city has a database that records the inventory of the regional warehouse and a group of salespersons that rely on the database for their sales activities. Each city also stores replications of databases of other cities. Therefore, a salesperson can also sale things stored in other cities' inventory databases, although majority of sales will be from the local inventory database. The aim of this paper is to develop a strategy that allows every part of the Web-based sales system to continue its operations during a network partitioning. When the network partitioning is recovered, a reconciliation process will bring the system to a consistent state. operations. In the back end, we use Java Database Connectivity (JDBC) for the servers in the transaction management system to access the physical data sources in various locations. This paper is structured as follows. In Section 2, we describe the background and the architecture of our Web-based sales system. In Section 3 we present the replication strategy for normal operations. The replication strategy for dealing with network partitioning and recovery is described in Section 4. Section 5 discusses some performance issues. In Section 6 we conclude the paper.

Permasalahan yang ada pada server adalah banyaknya user yang mengakses dalam waktu bersamaan. Untuk mengatasinya dapat digunakan konsep cluster server. Metode yang digunakan dalam artikel ini adalah membangun 3 cluster server web  dan 1 load balancer dari 4 buah Nanopi2 serta  mengimplementasikan algoritma round robin dalam pengaturan kerjanya. Hasil yang diperoleh adalah bahwa terjadi pembagian beban trafik yang berimbang di antara 3 server dengan rata-rata pada saat server menerima request dari client adalah 33.57%, 32.64%, dan 33.8%, serta rata-rata pada saat server memberikan response adalah 33.47%, 34.14%, dan 35.35%

Grid computing generally involves the aggregation of geographically distributed resources in the context of a particular application. As such resources can exist within different administrative domains, requirements on the communication network must also be taken into account when performing meta-scheduling, migration or monitoring of jobs. Similarly, coordinating efficient interaction between different domains should also be considered when performing such meta-scheduling of jobs. A strategy to perform peer-to-peer-inspired meta-scheduling in Grids is presented. This strategy has three main goals: (1) it takes the network characteristics into account when performing meta-scheduling; (2) communication and query referral between domains is considered, so that efficient meta-scheduling can be performed; and (3) the strategy demonstrates scalability, making it suitable for many scientific applications that require resources on a large scale. Simulation results are presented that demonstrate the usefulness of this approach, and it is compared with other proposals from literature.

The most frequent challenge faced by mobile user is stay connected with online data, while disconnected or poorly connected store the replica of critical data. Nomadic users require replication to store copies of critical data on their mobile machines. Existing replication services do not provide all classes of mobile users with the capabilities they require, which include: the ability for direct synchronization between any two replicas, support for large numbers of replicas, and detailed control over what files reside on their local (mobile) replica. Existing peer-topeer solutions would enable direct communication, but suffers from dramatic scaling problems in the number of replicas, limiting the number of overall users and impacting performance. Roam is a replication system designed to satisfy the requirements of the mobile user. Roam is based on the Ward Model, replication architecture for mobile environments. Using the Ward Model and new distributed algorithms, Roam provides a scalable replication solution for the mobile user. We describe the motivation, design, and implementation of Roam and report its performance. Replication is extremely important in mobile environments because nomadic users require local copies of important data.

However, cluster computing did not gain momentum until the convergence of three important trends in the 1980s: high-performance microprocessors, high-speed networks, and standard tools for high performance distributed computing. A possible fourth trend is the increasing need of computing power for computational science and commercial applications coupled with the high cost and low accessibility of traditional supercomputers. These four building blocks are also known as killer-microprocessors, killer-networks, killer-tools, and killer-applications, respectively. The recent advances in these technologies and their availability as cheap and commodity components are making clusters or networks of computers such as Personal Computers (PCs), workstations, and Symmetric Multiple-Processors (SMPs) an appealing solution for cost-effective parallel computing. Clusters, built using commodity-off-the-shelf (COTS) hardware components as well as free, or commonly used, software, are playing a major role in redefining the concept of supercomputing. And consequently, they have emerged as mainstream parallel and distributed platforms for high-performance, high-throughput and high-availability computing. The trend in parallel computing is to move away from traditional specialized supercomputing platforms, such as the Cray/SGI T3E, to cheaper and general purpose systems consisting of loosely coupled components built up from single or multiprocessor PCs or workstations. This approach has a number of advantages, including being able to build a platform for a given budget that is suitable for a large class of applications and workloads.

An electronic commerce (EC) process is a business process and defining it as a workflow provides all the advantages that come with this technology. Yet electronic commerce processes place certain demands on the workflow technology like the distribution of the load of the workflow engine to multiple servers, dynamic modification of workflows for adaptability, openness and availability. In this paper we propose a workflow system architecture to address these issues. The componentwise architecture of the system makes it possible to incorporate the functionality and thus the complexity only when it is actually needed. The infrastructure of the system is based on CORBA 2.0 where methods are invoked through XML. The clients of the system are coded as network transportable applets written in Java so that the end user can activate workflow components through the workflow domain manager over the network. The system provides high availability by replicating the component server repository and the workflow domain manager. We also discuss how this architecture can be used in building an electronic marketplace.

This study evaluates internet control message protocol (ICMP) flood detection and mitigation in software-defined networks (SDN) using an SDN architecture with sFlow-RT for real-time traffic monitoring. OpenFlow switches and sFlow agents detect malicious patterns, following the prepare, plan, design, implement, operate, optimize (PPDIOO) methodology. Unlike prior approaches, this system leverages SDN programmability and sFlow-RT's real-time analytics to reduce ICMP packets from 311,130.2 to 99 and latency by 80%, outperforming traditional methods in speed and responsiveness. It ensures network availability, with practical benefits for large-scale networks like internet service providers (ISPs). However, sFlow sampling rates may affect accuracy in high-speed networks, and a single OpenDaylight (ODL) controller limits generalizability. Future work should test alternative controllers and extend to other DDoS types like user datagram protocol (UDP) floods in diverse topologies.

We present Kaleidoscope an innovative system that supports live forensics for application performance problems caused by either individual component failures or resource contention issues in large-scale distributed storage systems. The design of Kaleidoscope is driven by our study of I/O failures observed in a peta-scale storage system anonymized as PetaStore. Kaleidoscope is built on three key features: 1) using temporal and spatial differential observability for end-to-end performance monitoring of I/O requests, 2) modeling the health of storage components as a stochastic process using domain-guided functions that accounts for path redundancy and uncertainty in measurements, and, 3) observing differences in reliability and performance metrics between similar types of healthy and unhealthy components to attribute the most likely root causes. We deployed Kaleidoscope on PetaStore and our evaluation shows that Kaleidoscope can run live forensics at 5-minute intervals and pinpoint the...

The control of phytoplankton growth is mainly related to the availability of light and nutrients. Both may select phytoplankton species, but only if they occur in limiting amounts. During the last decade, the functional groups approach, based on the physiological, morphological and ecological attributes of the species, has proved to be a more efficient way to analyze seasonal changes in phytoplankton biomass. We analysed the dynamics of the phytoplankton functional groups sensu Reynolds, recognising the driving forces (light, mixing regime, and nutrients) in the Sau Reservoir, based on a oneeyear cycle (monthly surface-water sampling). The Sau Reservoir is a Mediterranean water-supply reservoir with a canyon-shaped basin and a clear and mixed epilimnion layer. The long stratification period and high light availability led to high phytoplankton biomass (110.8 fresh-weight mg L À1 ) in the epilimnion during summer. The reservoir showed P-limitation for phytoplankton growth in this period. All functional groups included one or more species (X2-Rhodomonas spp.; Y-Cryptomonas spp.; F-Oocystis lacustris; K-Aphanocapsa spp.) selected by resources, especially phosphorus. Species of Cryptomonas (group Y) dominated during the mixing period (winter season) in conditions of low light and relatively high availability of dissolved nutrients. Increases in water-column stability during spring stratification led to phytoplankton biomass increases due to the dominance of small flagellate functional groups (X2 and X3, chrysophyceans). The colonial chlorophycean O. lacustris (group F) peaked during the mid-summer stratification, when the mixed epilimnion was clearly depleted in nutrients, especially SRP. High temperature and increases in nutrient concentration during the end-summer and mid-autumn resulted in a decrease of green algae (group F) and increase of Aphanocapsa spp. (cyanobacteria, group K) and dinoflagellates (group L o ). The study also revealed the important role of physical processes in the seasonal gradient, in selecting phytoplankton functional groups, and consequently in the assessment of ecological status. The Q index (assemblage index) based on functional

Cloud computing alters the way organizations manage and deploy their IT resource. It provides an organization with scalable, inexpensive, and flexible options. The complexity and dynamic nature of cloud environments pose a challenge to maintaining high availability at all times, especially when the system fails or a disaster arises. The legacy techniques of disaster recovery, fault tolerance, and high availability leave behind much to be desired. These techniques are mostly static, slow to respond, and have a dismal ability to adapt to continuously changing conditions in contemporary cloud systems. Such techniques largely depend on manual configurations and predefined policies; resulting in lots of inefficiencies and increases in the risk of service downtime. This research investigates the way Artificial Intelligence (AI) changes the paradigm on cloud resilience to promote adoption of intelligent systems for guaranteed disaster recovery, better fault-tolerant behavior, or transparent high availability. With machine learning algorithms, AI-based cloud services utilize large data volumes to reveal patterns within system logs, performance metrics, and user behavior data; thereby offering real-time anomaly detection and predictive failure analysis. For example, techniques like predictive analytics help cloud providers predict likely system outages, optimize the resources to be used, and automate failover processes (Xu et al., 2021; Lee & Kumar, 2022). AI-aided disaster recovery techniques employ complex algorithms to produce an adaptive backup mechanism, thereby minimizing loss and reducing restoration time. Fault tolerance in AI cloud systems comes from intelligent error correction, automatic isolation of faults, and self-healing features, i.e. repair of faults without the need for human supervision (Chen et al., 2020). Besides that, AI also contributes to high availability through intelligent load balancing, which ensures that at any given time, resources are optimally distributed throughout the network to sustain continuous service even during peak demand or unanticipated failures (Patel & Zhang, 2023). The approach is a comprehensive review of the various existing literature on the topic, empirical analysis of the current AI-driven cloud solutions available in the market, and case studies for comparison analysis on the different AI systems. The study scenario reveals that AI-driven solutions noticeably reduce downtimes, lead to improved recovery times, and contribute to overall system reliability as compared to traditional methods. However, other areas include model bias, data privacy, and continuous training of AI models. This study expands the trends of AI in the field of cloud computing by documenting the significance of intelligent systems in bridging traditional weaknesses of resilience strategies. It further signifies the need for AI into predictive maintenance, automated disaster response, and proactive fault management of rapidly changing dynamic cloud environments. Future studies will focus on AI integration along with edge computing and blockchain technologies for even more robust and secure services in cloud operations.

The approach is a comprehensive review of the various existing literature on the topic, empirical analysis of the current AI-driven cloud solutions available in the market, and case studies for comparison analysis on the different AI systems. The study scenario reveals that AI-driven solutions noticeably reduce downtimes, lead to improved recovery times, and contribute to overall system reliability as compared to traditional methods. However, other areas include model bias, data privacy, and continuous training of AI models. This study expands the trends of AI in the field of cloud computing by documenting the significance of intelligent systems in bridging traditional weaknesses of resilience strategies. It further signifies the need for AI into predictive maintenance, automated disaster response, and proactive fault management of rapidly changing dynamic cloud environments. Future studies will focus on AI integration along with edge computing and blockchain technologies for even more robust and secure services in cloud operations.