Virtualized Data Centers Research Articles

A platform for FPGA virtualization in clouds and data centers

Though Field-Programmable Gate Arrays (FPGAs) have achieved significant performance gains for many application domains, implementing applications on FPGAs still remains a non-trivial task. This is especially true for FPGAs in a Data Center or a cloud. In this work a new platform for virtualizing FPGAs has been developed. It allows the rapid deployment (or porting) of applications on cloud-based or data-center attached FPGAs. A complete platform prototype has been implemented to evaluate the area, speed, and overhead of the proposed platform. The proposed platform provides a general abstract interface to any user's design (not domain specific) and supports dynamic partial reconfiguration (so designs can be added to an FPGA that have other applications running) at comparable overhead to other notable platforms. Experimental results using a streamed application in a cloud-like environment, showed that the proposed platform is a very viable computing option (in terms of throughput) for suitable applications compared to conventional server-based or virtual-machine based SW implementations.

DADTA: A novel adaptive strategy for energy and performance efficient virtual machine consolidation

Large-scale virtualized data centers are increasingly becoming the norm in our data-intensive society. One pressing challenge is to reduce energy consumption in such data centers for edge computing deployment, which would have flow-on effects on reducing the operating costs and carbon dioxide emissions. Dynamic virtual machine consolidation is an effective way to improve resource utilization and energy efficiency. In this paper, a comprehensive strategy is proposed, which is based on time-series forecasting approach. In this strategy, specific adjustment of threshold is applied to adapt the dynamic workload. We then use a real-world dataset (i.e. workload trace in Google) for evaluation, whose findings demonstrate that our strategy outperforms other benchmarks.

Fully SDN-Enabled All-Optical Architecture for Data Center Virtualization with Time and Space Multiplexing

Virtual data center (VDC) solutions provide an environment that is able to quickly scale up, and where virtual machines and network resources can be quickly added on-demand through self-service procedures. VDC providers must support multiple simultaneous tenants with isolated networks on the same physical substrate. The provider must make efficient use of its available physical resources while providing high-bandwidth and low-latency connections to tenants with a variety of VDC configurations. This paper utilizes state-of-the-art optical network elements to provide high-bandwidth optical interconnections and develop a VDC architecture to slice the network and the compute resources dynamically, to efficiently divide the physical network between tenants. We present a data center virtualization architecture with a softwaredefined networking controlled all-optical data plane combining optical circuit switching and a time-shared optical network. Developed network orchestration dynamically translates and provisions VDCs requests onto the optical physical layer. The experimental results show the provisioned bandwidth can be varied by adjusting the number of time slots allocated in the time-division multiplexing (TDM) network. These results lead to recommendations for provisioning TDM connections with different performance characteristics. Moreover, application-level optical switch reconfiguration time is also evaluated to fully understand the impact on application performance in VDC provision. The experimental demonstration confirmed that the developed VDC approach introduces negligible delay and complexity on the network side.

Self-adaptive architecture for virtual machines consolidation based on probabilistic model evaluation of data centers in Cloud computing

By employing the virtual machines (VMs) consolidation technique at a virtualized data center, optimal mapping of VMs to physical machines (PMs) can be performed. The type of optimization approach and the policy of detecting the appropriate time to implement the consolidation process are influential in the performance of the consolidation technique. In a majority of researches, the consolidation approach merely focuses on the management of underloaded or overloaded PMs, while a number of VMs could also be in an underload or overload state. Managing an abnormal state of VM results in the postponement of PM getting into an abnormal state as well and affects the implementation time of the consolidation process. For the aim of optimal VM consolidation in this research, a self-adaptive architecture is presented to detect and manage underloaded and overloaded VMs /PMs in reaction to workload changes in the data center. The goal of consolidation process is employing the minimum number of active VMs and PMs, while guaranteeing the quality of service (QoS). Assessment criteria of QoS are two parameters including average number of requests in the PM buffer and average waiting time in the VM. To evaluate these two parameters, a probabilistic model of the data center is proposed by applying the queuing theory. The assessment results of the probabilistic model form a basis for decision-making in the modules of the proposed architecture. Numerical results obtained from the assessment of the probabilistic model via discrete-event simulator under various parameter settings confirm the efficiency of the proposed architecture in achieving the aims of the consolidation process.

Efficient virtual network function placement strategies for Cloud Radio Access Networks

The new generation of 5G mobile services place stringent requirements for cellular network operators in terms of latency and costs. The latest trend in radio access networks (RANs) is to pool the baseband units (BBUs) of multiple radio base stations and to install them in a centralized infrastructure, such as a cloud, for statistical multiplexing gains. The technology is known as Cloud Radio Access Network (CRAN). Since cloud computing is gaining significant traction and virtualized data centers are becoming popular as a cost-effective infrastructure in the telecommunication industry, CRAN is being heralded as a candidate technology to meet the expectations of radio access networks for 5G. In CRANs, low energy base stations (BSs) are deployed over a small geographical location and are connected to a cloud via finite capacity backhaul links. Baseband processing unit (BBU) functions are implemented on the virtual machines (VMs) in the cloud over commodity hardware. Such functions, built in software, are termed as virtual functions (VFs). The optimized placement of VFs is necessary to reduce the total delays and minimize the overall costs to operate CRANs. Our study considers the problem of optimal VF placement over distributed virtual resources spread across multiple clouds, creating a centralized BBU cloud. We propose a combinatorial optimization model and the use of two heuristic approaches, which are, branch-and-bound (BnB) and simulated annealing (SA) for the proposed optimal placement. In addition, we propose enhancements to the standard BnB heuristic and compare the results with standard BnB and SA approaches. The proposed enhancements improve the quality of the solution in terms of latency and cost as well as reduce the execution complexity significantly. We also determine the optimal number of clouds, which need to be deployed so that the total links delays, as well as the service migration delays, are minimized, while the total cloud deployment cost is within the acceptable limits.

Demonstration of application-driven network slicing and orchestration in optical/packet domains: on-demand vDC expansion for Hadoop MapReduce optimization.

Nowadays, it is common for service providers (SPs) to leverage hybrid clouds to improve the quality-of-service (QoS) of their Big Data applications. However, for achieving guaranteed latency and/or bandwidth in its hybrid cloud, an SP might desire to have a virtual datacenter (vDC) network, in which it can manage and manipulate the network connections freely. To address this requirement, we design and implement a network slicing and orchestration (NSO) system that can create and expand vDCs across optical/packet domains on-demand. Considering Hadoop MapReduce (M/R) as the use-case, we describe the proposed architectures of the system's data, control and management planes, and present the operation procedures for creating, expanding, monitoring and managing a vDC for M/R optimization. The proposed NSO system is then realized in a small-scale network testbed that includes four optical/packet domains, and we conduct experiments in it to demonstrate the whole operations of the data, control and management planes. Our experimental results verify that application-driven on-demand vDC expansion across optical/packet domains can be achieved for M/R optimization, and after being provisioned with a vDC, the SP using the NSO system can fully control the vDC network and further optimize the M/R jobs in it with network orchestration.

Real-time logs in virtual data-center

Real-time logs in virtual data-center

Dragonfly addressing model for software defined networks based on datacenters

With the advancement of technology, virtualization has become very important for Information Technology (IT) experts. Network Functions Virtualization (NFV) means to address issues resulting from complex hardware-based appliances by developing standard IT virtualization technologies. Software Defined Networking (SDN) solidifies the advantages of datacenter virtualization, increases resource flexibility and utilization, and reduces infrastructure costs and overhead. Datacenter networks should have the ability to guarantee high throughput and resiliency. For such reasons, typical datacenter networks (e.g. Fat Tree) have been evolved to high-radix networks (e.g. Dragonfly). This work aims to investigate how SDN and NFV can improve the advantages of datacenter virtualization by utilizing datacenter topologies such as Dragonfly (DF) topology and Fat Tree (FT) topology in SDN, thus expanding resource flexibility and utilization and diminishing infrastructure costs and overhead. By using Dragonfly topology, the cost is reduced and better scalability is introduced compared to the folded clos networks such as Fat Tree. Here in, a novel addressing scheme is proposed for Dragonfly topology with simulation results included utilizing Mininet, which incorporates MiniEdit that is used to create and run network simulations.

Server consolidation techniques in virtualized data centers of cloud environments: A systematic literature review

SummaryAt the virtualized data centers, services are presented by active virtual machines (VMs) in physical machines (PMs). The manner in which VMs are mapped to PMs affects the performance of data centers and the energy efficiency. By employing the server consolidation technique, it is possible to configure the VMs on a smaller number of PMs, while the quality of service is guaranteed. In this way, the rate of active PM utilization increases and fewer active PMs would be required. Moreover, the server consolidation technique reacts to the management of underloaded and overloaded PMs by using the VM migration technology. Considering the capabilities of the server consolidation technique and its role in developing the cloud computing infrastructure, many researches have been conducted in this context. Still, a comprehensive and systematic study has not yet been performed on various consolidation techniques to check the capabilities, advantages, and disadvantages of current approaches. In this paper, a systematic study is conducted on a number of credible researches related to server consolidation techniques. In order to do so and by studying the selected works, proposed solutions are categorized based on the type of decision for running the consolidation algorithm in 4 groups of static method, dynamic method, prediction‐based dynamic method, and hybrid method. Thereafter, the advantages and disadvantages of suggested approaches are studied and compared in each research by specifying the technique and idea applied therein. In addition, by categorizing aims of researches and specifying assessment parameters, optimization approaches and type of architecture, a possibility has been provided to get familiarized with the views of the researchers.

Stark Broadening of Cr III Spectral Lines: DO White Dwarfs

Using the modified semiempirical method of Dimitrijević and Konjević, Stark widths have been calculated for six Cr III transitions, for an electron density of 10 17 cm ‒ 3 and for temperatures from 5000–80,000 K. Results have been used for the investigation of the influence of Stark broadening on spectral lines in cool DO white dwarf atmospheres. Calculated Stark widths will be implemented in the STARK-B database, which is also a part of the Virtual Atomic and Molecular Data Center (VAMDC).

The Development and Study of the Methods and Algorithms for the Classification of Data Flows of Cloud Applications in the Network of the Virtual Data Center

The Development and Study of the Methods and Algorithms for the Classification of Data Flows of Cloud Applications in the Network of the Virtual Data Center

Azure Networking

To create the Azure cloud, we imagined and built a massive cloud network, literally from the ground up. Azure creates and sustains a virtual data center for every tenant, under the tenant's control, meeting the tenant's goals for high security, reliability, ease of use, and performance. Building all this calls for innovation across hardware and software. I'll discuss key challenges and solutions, as well as demo new functionality.

Centralized real-time logs investigation in virtual data-center

Penetration testing is a specialized security auditing methodology where a tester simulates an attack on a secured system. The main theme of this paper itself reflects how one can collect the massive amount of log files which are generated among virtual datacenters in real time which in turn also posses invisible information with excessive organization value. Such testing usually ranges across all aspects concerned to log management across a number of servers among virtual data centers. In fact, Virtualization limits the costs by reducing the need for physical hardware systems. Instead, require high-end hardware for processing. In the real-time scenario, we usually come across multiple logs among VCenter, ESXi, a VM which is very typical for performing manual analysis with a bit more time-consuming. Instead of configuring secure-ids automatically in a Centralized log management server gains a powerful full insight. Along with using accurate search algorithms, fields searching, which includes title, author, and also content comes out of searching, sorting fields, multiple-index search with merged results simultaneously updates files, with joint results grouping automatically configures few plugs among search engine file formats were effective measures in an investigation. Finally, by using the Flexibility Network Security Monitor, Traffic Investigation, offensive detection, Log Recording, Distributed inquiry with full program's ability can export data to a variety of visualization dashboard which exactly needed for Log Investigations across Virtual Data Centers in real time.

Improving the energy efficiency of virtual data centers in an IT service provider through proactive fuzzy rules-based multicriteria decision making

A proactive multicriteria mechanism for virtual data center optimization through server consolidation is proposed. In contrast with previous works where heuristic mechanisms were designed using expert knowledge, the new proactive approach uses multiobjective evolutionary algorithms to learn fuzzy rule-based systems that determine optimal reallocation decisions according to the preferences of the data center operator and a prediction of the load. Experimental evaluations based on an actual IT service provider show that the proactive mechanism is capable of improving energy savings compared to commercial hypervisors while complying with service provider’s preferences and constraints.

Nxt-Max: for supporting VDC-based maximum redundant bandwidth allocation in cloud datacenter

In cloud datacenter, work-conserving bandwidth offering benefits the network sharing of multiple virtual datacenters (VDCs). The lack of concrete network resources prevents tenants from predicting lower bounds on the performance of their applications. Prior works concentrate on efficient and scalable bandwidth allocation algorithms for VDCs. However, per-VDC redundant bandwidth is ignored, which is crucial to work-conserving bandwidth offering. In this paper, Nxt-Max, a VDC-based redundant bandwidth allocation framework is designed that ensures per-VDC maximum redundant bandwidth allocation by integrating online allocation with offline allocation. To make online bandwidth allocation efficient, a heuristic online parallel bandwidth allocation algorithm is proposed by dividing the whole allocation spaces into independent pods. Coupled with smart offline adjustment, the released network graph, and greedily migrate VDCs with the least redundant bandwidth are constructed, advancing the overall underlying network utilization. Simulations demonstrate that VDC allocation achieves high network utilization, low time complexity, and per-VDC maximum bandwidth allocation.

Stark Broadening of Se IV, Sn IV, Sb IV and Te IV Spectral Lines

Stark broadening parameters, line width and shift, are needed for investigations, analysis and modelling of astrophysical, laboratory, laser produced and technological plasmas. Especially in astrophysics, due to constantly increasing resolution of satellite borne spectrographs, and large terrestrial telescopes, data on trace elements, which were previously insignificant, now have increasing importance. Using the modified semiempirical method of Dimitrijević and Konjević, here, Stark widths have been calculated for 2 Se IV, 6 Sn IV, 2 Sb IV and 1 Te IV transitions. Results have been compared with existing theoretical data for Sn IV. Obtained results will be implemented in the STARK-B database, which is also a part of Virtual atomic and molecular data center (VAMDC).

Live Migration for Multiple Correlated Virtual Machines in Cloud-Based Data Centers

With the development of cloud computing, virtual machine migration is emerging as a promising technique to save energy, enhance resource utilizations, and guarantee Quality of Service (QoS) in cloud datacenters. Most of existing studies on the virtual machine migration, however are based on a single virtual machine migration. Although there are some researches on multiple virtual machines migration, the author usually does not consider the correlation among these virtual machines. In practice, in order to save energy and maintain system performance, cloud providers usually need to migrate multiple correlated virtual machines or migrate the entire virtual datacenter (VDC) request. In this paper, we focus on the efficient online live migration of multiple correlated VMs in VDC requests, for optimizing the migration performance. To solve this problem, we propose an efficient VDC migration algorithm (VDC-M). We use the US-wide US National Science Foundation (NSF) network as substrate network to conduct extensive simulation experiments. Simulation results show that the performance of the proposed algorithm is promising in terms of the total VDC remapping cost, the blocking ratio, the average migration time and the average downtime.

Delay-based virtual congestion control in multi-tenant datacenters

With the evolution of cloud computing and virtualization, the congestion control of virtual datacenters has become the basic issue for multi-tenant datacenters transmission. Regarding to the friendly conflict of heterogeneous congestion control among multi-tenant, this paper proposes a delay-based virtual congestion control, which translates the multi-tenant heterogeneous congestion control into delay-based feedback uniformly by setting the hypervisor translation layer, modifying three-way handshake of explicit feedback and packet loss feedback and throttling receive window. The simulation results show that the delay-based virtual congestion control can effectively solve the unfairness of heterogeneous feedback congestion control algorithms.

Inside a VAMDC data node—putting standards into practical software

Access to molecular and atomic data is critical for many forms of remote sensing analysis across different fields. Many atomic and molecular databases are however highly specialised for their intended application, complicating querying and combination data between sources. The Virtual Atomic and Molecular Data Centre, VAMDC, is an electronic infrastructure that allows each database to register as a ‘node’. Through services such as VAMDC’s portal website, users can then access and query all nodes in a homogenised way. Today all major Atomic and Molecular databases are attached to VAMDC This article describes the software tools we developed to help data providers create and manage a VAMDC node. It gives an overview of the VAMDC infrastructure and of the various standards it uses. The article then discusses the development choices made and how the standards are implemented in practice. It concludes with a full example of implementing a VAMDC node using a real-life case as well as future plans for the node software.

Programmable OPS/OCS hybrid data centre network

Abstract On the basis of profound understanding of data center (DC) traffic demands and optical switching technologies, we present a hybrid optical network design for future data center network (DCN). Such design integrates optical circuit switching (OCS) and optical packet switching (OPS) schemes via hybrid Top-of-the-Rack (ToR) switches which provide flexible function-switchover between different traffic patterns in the DCN. Simulations of network behaviors under such DC traffic loads indicate that the proposed OPS/OCS DCN can effectively improve the network performance. Moreover, via a preliminary analysis of OCS and OPS network configurations, the construction of hybrid DCN is also proved as the most cost- and energy-efficient way for DCN upgrading while offering a promised quality of service. An experimental demonstration shows a complete implementation of data center virtualization in the proposed hybrid data center network.