On cloud security requirements, threats, vulnerabilities and countermeasures: A survey

Cloud computing-enabled healthcare opportunities, issues, and applications: a systematic review

Reliability and high availability have always been a major concern in distributed systems. Providing highly available and reliable services in cloud computing is essential for maintaining customer confidence and satisfaction and preventing revenue losses. Although various solutions have been proposed for cloud availability and reliability, but there are no comprehensive studies that completely cover all different aspects in the problem. This paper presented a ‘Reference Roadmap’ of reliability and high availability in cloud computing environments. A big picture was proposed which was divided into four steps specifying through four pivotal questions starting with ‘Where?’, ‘Which?’, ‘When?’ and ‘How?’ keywords. The desirable result of having a highly available and reliable cloud system could be gained by answering these questions. Each step of this reference roadmap proposed a specific concern of a special portion of the issue. Two main research gaps were proposed by this reference roadmap.

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Reliability and high availability in cloud computing environments: a reference roadmap

Cloud Computing has been used by different types of clients because it has many advantages, including the minimization of infrastructure resources costs, and its elasticity property, which allows services to be scaled up or down according to the current demand. From the Cloud provider point-of-view, there are many challenges to be overcome in order to deliver Cloud services that meet all requirements defined in Service Level Agreements (SLAs). High availability has been one of the biggest challenges for providers, and many services can be used to improve the availability of a service, such as checkpointing, load balancing, and redundancy. Beyond services, we can also find infrastructure and middleware solutions. This systematic review has as its main goal to present and discuss high available (HA) solutions for Cloud Computing, and to introduce some research challenges in this area. We hope this work can be used as a starting point to understanding and coping with HA problems in Cloud.

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High availability in clouds: systematic review and research challenges

The technology of cloud computing is growing very quickly, thus it is required to manage the process of resource allocation. In this paper, load balancing algorithm based on honey bee behavior (LBA_HB) is proposed. Its main goal is distribute workload of multiple network links in the way that avoid underutilization and over utilization of the resources. This can be achieved by allocating the incoming task to a virtual machine (VM) which meets two conditions; number of tasks currently processing by this VM is less than number of tasks currently processing by other VMs and the deviation of this VM processing time from average processing time of all VMs is less than a threshold value. The proposed algorithm is compared with different scheduling algorithms; honey bee, ant colony, modified throttled and round robin algorithms. The results of experiments show the efficiency of the proposed algorithm in terms of execution time, response time, makespan, standard deviation of load, and degree of imbalance.

Honey Bee Based Load Balancing in Cloud Computing

Content Delivery Networks have gained a popular role among application service providers (ASPs) and infrastructural companies A CDN is an overlay network that gives more control of asset delivery by strategically placing servers closer to the end-user, reducing response time and network congestion Many strategies have been proposed to deal with aspects inherent to the CDN distribution model Though mostly very effective, a traditional CDN approach of statically positioned elements often fails to meet quality of experience (QoE) requirements when network conditions suddenly change In this paper, we introduce the idea of CDN virtualization The goal is to allow programmatically modification in CDN infrastructure designed for video distribution, adapting it to new operating conditions We developed a complete simulator focused on CDN overlay network characteristics where we implemented several approaches for each of the CDN elements Our results show a decrease of 20% in startup delay and network usage

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A case for virtualization of content delivery networks

Today, most innovation on Information Technology and Communication is cloud-centric and an increasing number of organizations believe that this transition is ever more unavoidable. With this increased demand for Cloud services, providers are facing many challenges regarding how to avoid outages and optimization of resource management since they impact directly in costs and profits. In this paper, we propose the cost-based allocation (CBA), a resource allocation system that takes into consideration the minimum availability level required by the user, and the minimum cost to allocate resources while complying with the service availability forum redundancy models. Results show that, considering occupation and cost metrics, our CBA algorithm presents the best overall performance between evaluated strategies.

Resource allocation based on redundancy models for high availability cloud

Today's mobile network architecture lacks the flexibility to efficiently handle the fast increasing amount of data traffic. SDN could potentially provide the required flexibility in future mobile architectures, however its introduction into the existing architecture is challenging. In this paper we propose a solution to improve the mobile backhaul's flexibility based on SDN, compatible with the current architecture, focusing on the transparent in-network caching's use case. We explore the design space in terms of function placement, and propose a scalable solution for in-network caching based on stateless DPI and stateful connection tracking. We implemented a prototype of the proposed solution to evaluate its impact on MPEG DASH streaming performance. Our experimental results show that the delay introduced by our module is less than 5ms for 99% of the packets, which is negligible in today's LTE networks, and the slight negative impact on streaming rate selection is easily outweighed by the increased flexibility.

Enabling transparent caching in LTE mobile backhaul networks with SDN

Cloud outages, no matter how long, are responsible for large financial losses. Cloud providers look for solutions that provide high availability even in failure cases. Redundancy has been often used as an alternative; however it has a cost, and depending on the redundancy model, we can have different levels of availability. Beyond that, adding more resources also means adding more complexity and more point of failures. In this paper, we propose a risk-based model for estimating the availability of a redundancy setup. In order to analyze our model, we conduct Monte Carlo simulations and results show that for all models, the number of applications we deploy in a Cloud environment impacts on its availability.

Moises Rodrigues

Papers

High availability in clouds: systematic review and research challenges

A case for virtualization of content delivery networks

Resource allocation based on redundancy models for high availability cloud

Enabling transparent caching in LTE mobile backhaul networks with SDN

Risk-based model for availability estimation of SAF redundancy models