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When provided with more powerful or extra hardware, state-of-the-art Byzantine fault-tolerant (BFT) agreement protocols are unable to effectively exploit the additional computing resources: On the one hand, in settings with heterogeneous servers existing protocols cannot fully utilize servers with higher performance capabilities. On the other hand, using more servers than the minimum number of replicas...
In order to support large volume of transactions and number of users, as estimated by the load demand modeling, a system needs to scale in order to continue to satisfy required quality attributes. In particular, for systems exposed to the Internet, scaling up may increase the attack surface susceptible to malicious intrusions. The new proactive approach based on the concept of Moving Target Defense...
Cloud computing is an emerging technology which enables the cloud users to access the computing resources without having to pay huge capital expenses to scale up the IT infrastructure and reduces the management cost, in both hardware and software. A cloud introduces a resource rich computing model with features such as flexibility, pay per use, elasticity, scalability, and others. In this context,...
This paper aims at the development of a cloud services provisioning framework by developing a dynamic priority job scheduler cum load-balancer for the cloud. The main motive of this paper is to provide a means of managing the job requests in a flexible and cost-effective way, both for the customer and the cloud service provider. In order to make the cloud scalable and adaptable to the changing needs...
Cloud computing is the promising technology that provides computational, storage, network and database resources by employing the virtualization technology in the infrastructure layer. Nowadays, most of the applications are hosted in the multi-tenant based virtualized cloud environment. Scalability is the challenging task in this environment for effective utilization of the resources and to improve...
A non-invasive, cloud-agnostic approach is demonstrated for extending existing cloud platforms to include checkpoint-restart capability. Most cloud platforms currently rely on each application to provide its own fault tolerance. A uniform mechanism within the cloud itself serves two purposes: (a) direct support for long-running jobs, which would otherwise require a custom fault-tolerant mechanism...
Nowadays, while the storage requirement of virtual machine images generated in cloud infrastructures can be potentially reduced by the deduplication, considering their scale and intensity, the deduplication cluster is demanded. Therefore, in this paper we present SDVC, a scalable deduplication cluster for virtual machine images in cloud. SDVC offers both vertical and horizontal scalability. The horizontal...
The recent decade witnesses the prevalence of hybrid storage systems that offer storage based on diverse storage devices to achieve both cost savings and performance improvements. However, there have been little of studies focusing on the challenging scenario of providing hybrid block storage for Virtual Machines (VMs), which is subject to several stringent requirements such as availability and scalability...
Honeynet represents the new theory in network protection. Unlike purely defensive methods such as Intrusion Detection Systems (IDS), Data Encryption and Firewalls that try to avoid interaction with the attacker, Honeynet is based on the idea of interaction with the attacker. During this interaction, the Honeynet records all of the attacker's actions and tools used without the attacker knowing, representing...
OS-level virtualization generates a minimal start-up and run-time overhead on the host OS and thus suits applications that require both good isolation and high efficiency. However, multiple-member applications required for forming a system may need to occasionally communicate across this isolation barrier to cooperate with each other while they are separated in different VMs to isolate intrusion or...
The smallest instance offered by Amazon EC2 comes with 615MB memory and a 7.9GB disk image. While small by today's standards, embedded web servers with memory footprints well under 100kB, indicate that there is much to be saved. In this work we investigate how large VM-populations the open Stack hyper visor can be made to sustain, by tuning it for scalability and minimizing virtual machine images...
Cloud computing increases the level of connectivity between software applications. IT management applications delivered as a service may need to connect to tens of thousands of endpoint systems. In order to validate the application's reliability and performance at these very large scales, its scalability needs to be tested before being deployed in the cloud. We use an emulation approach, whereby endpoints...
Energy efficiency is an important issue for data centers given the amount of energy they consume yearly. However, there is still a gap of understanding of how exactly the application type and the heterogeneity of servers and their configuration impact the energy efficiency of data centers. To this end, we introduce the notion of Application Specific Energy Efficiency (ASEE) in order to rank energy...
Platform-as-a-Service is a cloud-based approach that provides enterprises with all the functionalities for developing, deploying, and administering services, without the burden of installing, configuring, and managing the underlying middleware, operating system, and hardware. In this context, scalability becomes a fundamental requirement, and appropriate solutions need to be studied and evaluated...
Although testing is a standard method for improving the quality of software, conventional testing methods often fail to detect faults. Concolic testing attempts to remedy this by automatically generating test cases to explore execution paths in a program under test, helping testers achieve greater coverage of program behavior in a more automated fashion. Concolic testing, however, consumes a significant...
Virtual machine (VM) provisioning is one of the fundamental components in virtualization-based cloud offerings. Modeling and analytically understanding the provisioning process is critical for the deployment and management of large-scale cloud. Based on extensive experiments on an example cloud system, we propose a queueing model to capture the important features related to scalability for the provisioning...
The growing adoption of virtualization in the enterprise environment has resulted in a couple of huge benefits, however, this has not been without its attendant problems and anomalies, such as performance tuning and erratic performance metrics, unresponsive virtualized systems, crashed virtualized servers, misconfigured virtual hosting platforms, amongst others. The focus of this research was the...
To investigate challenges of multi-tier application migration to Infrastructure-as-a-Service (IaaS) clouds we performed an experimental investigation by deploying a processor bound and input-output bound variant of the RUSLE2 erosion model to an IaaS based private cloud. Scaling the applications to achieve optimal system throughput is complex and involves much more than simply increasing the number...
As multi-core processors become increasingly mainstream, architects have likewise become more interested in how best to make use of the computing capacity of the CPU, for instance, through multiple simultaneous threads or processes of execution with OpenMP or MPI. At the same time, the increasingly mature and prevailing virtualization technique in server consolidation and HPC promotes the emergence...
Scalability is critical to the success of many enterprises currently involved in doing business on the Web and in providing information that may vary drastically from one time to another. Maintaining sufficient resources just to meet peak requirements can be costly. Cloud computing provides a powerful computing model that allows users to access resources on-demand. In this paper, we will describe...
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