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Amazon Elastic Compute Cloud (EC2) gives access to resources in the form of virtual servers, also known as instances. EC2 Spot Instances (SIs) offer spare compute capacity at steep discounts compared to reliable and fixed price on-demand instances. The drawback, however, is that waiting time until requested spots become fulfilled can be incredible high. In this paper, we propose a container migration-based solution to enhance the reliability of virtual cluster computing environments built on top of non-reserved EC2 pricing model instances. We compare the performance of our algorithm by executing different resource provisioning plans for running real-life workflow applications, constrained by user-defined deadline and budget Quality of Service (QoS) parameters. The results show that our solution is able to successfully conclude almost 98% of workflow applications and more than 99% of workflow tasks for on-demand- and spot block-based virtual compute environments. For SI-based virtual compute environments, our solution achieves similar results, completing more than 98% of workflow applications, and over 99% of workflow tasks, for a worse-case scenario.

In most of the current commercial Clouds, resources are billed based on a time interval equal to one hour, as is the case of virtual machine (VM) instances on Amazon EC2. Such time interval is usually long, and yet the user has to pay for the whole last hour, even if he/she has only used a fraction of it, contradicting the pay-as-you-go model of Clouds. In this paper, we analyse the advantages of adopting alternative scheduling policies that exploit idle last time intervals, in terms of service cost to Cloud users and operating costs to Cloud providers. Using a real-life astronomy workflow application, constrained by user-defined Deadline and Budget quality of service (QoS) parameters, a set of online state-ofthe-art-based scheduling algorithms try different execution and resource provisioning plans. Our results show that exploitation of partially idle last time intervals can reduce the cost of service to the end user, and augments providers competitiveness up to 21.6% through energy efficiency improvement and consequent lowering of operational costs.

Cloud data centers have been progressively adopted in different scenarios, as reflected in the execution of heterogeneous applications with diverse workloads and diverse quality of service (QoS) requirements. Virtual machine (VM) technology eases resource management in physical servers and helps cloud providers achieve goals such as optimization of energy consumption. However, the performance of an application running inside a VM is not guaranteed due to the interference among co-hosted workloads sharing the same physical resources. Moreover, the different types of co-hosted applications with diverse QoS requirements as well as the dynamic behavior of the cloud makes efficient provisioning of resources even more difficult and a challenging problem in cloud data centers. In this paper, we address the problem of resource allocation within a data center that runs different types of application workloads, particularly CPU- and network-intensive applications. To address these challenges, we propose an interference- and power-aware management mechanism that combines a performance deviation estimator and a scheduling algorithm to guide the resource allocation in virtualized environments. We conduct simulations by injecting synthetic workloads whose characteristics follow the last version of the Google Cloud tracelogs. The results indicate that our performance-enforcing strategy is able to fulfill contracted SLAs of real-world environments while reducing energy costs by as much as 21%.

Virtualization technologies empower construction of flexible computing environments, promising an opportunity for energy and resource cost optimization, while enhancing system availability and achieving high performance. A crucial requirement for effective consolidation is to be able to efficiently utilize system resources for high-availability computing, and energy-efficiency optimization, so as to reduce operational costs and carbon footprints to the environment. In this work, we propose a consolidation technique to improve the performance of energy- and reliability-aware scheduling algorithms. For that, we carefully tune an energy optimization mechanism, which detects energy optimizing opportunities, and executes power- and failure-aware decision making algorithms to readjust virtual-to-physical mappings. We conduct simulations injecting synthetic jobs which characteristics follow the last version of the Google Cloud trace logs. The results indicate that our strategy improves work per Joule ratio in about 9.7%, as well working-efficiency in almost 15.6%, maintaining similar levels of completion jobs.