Service Level Agreement Constraints Research Articles

Power Aware Job Scheduling in Multi-Processor System with Service Level Agreements Constraints

Conventional hardware based per-component and system-wide power management methods can save more power consumptions if they are in assistance with software-level adaptation. Since the conventional coarse-grained methods are not adaptive to various fluctuating workload in real scenarios, the system performance can be deteriorated greatly if the objective is only to minimize the total power consumptions separately, despite of the violations of Service Level Agreements (SLAs). In this paper a fine-grained job-level power aware scheduling algorithm is proposed to minimize power consumption in multi-processor system with SLA constraints. Simulation results show that the proposed algorithm can save significant power consumptions while still providing SLAs guarantees and the performance degradation is acceptable. The results also show that fine-grained job-level power aware scheduling can achieve better power/performance balancing between multiple processors than coarse grained methods.

Trustworthy Web services provisioning for differentiated customer services

With the number of e-Business applications dramatically increasing, a service level agreement (SLA) will play an important part in Web services. The SLA is a combination of several quality of services (QoS), such as security, performance, and availability, agreed between a customer and a service provider. Most existing research addresses only one of these QoS metrics. Furthermore, in the case of the response time defined as one of QoS metrics for performance, only the average time to process and complete a job is typically used. Moreover, customer requests often need to be distinguished, with different request characteristics and customer's different service requirements. In this paper, we consider a set of computer resources used by a service broker to host enterprise applications for two classes of differentiated customer services subject to a service level agreement. We study three QoS metrics, namely, trustworthiness, a percentile response time, and availability. The percentile response time metric defines a value below which the end-to-end response time has to be for a given percent of time. We present an approach for resource optimization in such an environment that minimizes the total cost of computer resources while satisfying all these three QoS metrics in a trust-based resource provisioning problem which typically arises in Web services. We formulate the trust-based resource provisioning problem as an optimization problem under SLA constraints, and then solve it using an efficient numerical procedure.

Extending the OSI model for wireless battlefield networks: a design approach to the 8th Layer for tactical hyper-nodes

In this paper, we introduce the architecture and functionality of a new 8th layer that extends the well known 7-layer OSI model to implement adaptive networking by giving every critical node of a C4I network its own specialised Network Operation Centre (NOC) capability. We call these 'intelligent nodes' that adapt their behaviour and organisation through incorporation of these 8th layer hyper-nodes. The hyper-nodes achieve goal-seeking behaviour by satisfying Service Level Agreement constraints; they achieve sensing by way of polling SNMP MIB data describing overall NOC status; they capture experience through a memory mechanism for learned network management actions.

Dynamic service-level-agreement aware shared-path protection in WDM mesh networks

The notion of service level agreements (SLA) has been proposed to capture qualitatively and quantitatively defined performance contracts between service providers and their customers. How to provision satisfiable connections for customers according to their SLA parameters to avoid penalty as well as minimizing cost is one of the main concerns for a service provider. Connection reliability and restoration time are two important SLA parameters for a customer, and should be carefully considered in survivable wavelength-division-multiplexing (WDM) networks. A sound scheme should guarantee customers’ reliability and reduce restoration time while benefiting a service provider in resource efficiency. Under the SLA constraints and the assumption of single link failure, we first investigate a partial link-disjoint protection (PLDP) and analyze its availability and average restoration time. We then propose a dynamic constraint shared path protection (DCSP) algorithm in WDM mesh networks. Based on the basic ideas of the K-shortest path algorithm and PLDP, DCSP can provide differentiated services for customers according to their SLA parameters while being favorable for reducing average restoration time and optimizing resource utilization. Simulation results show that DCSP can efficiently guarantee the specific SLA requirements of customers with a slight increase in the blocking probability while still achieving spare resource sharing and restoration time optimizations.

Utilizing unreliable public resources for higher profit and better SLA compliance in computing utilities

Computing utilities are emerging as an important part of the infrastructure for outsourcing computer services. Fundamental to outsourcing is the notion of quality of service, which is defined by service level agreements (SLAs) between the computing utilities and clients. One of the major objectives of computing utilities is to maximize their net profit while maintaining customer loyalty. To achieve this objective, the computing utilities should meet or exceed their SLA constraints most of the time. Defining the SLAs conservatively might be one way of easily achieving these goals. However, by tuning the SLA parameters conservatively the computing utility might under utilize its resources with a resultant loss of revenue. Therefore, we can see two main issues with SLA management: designing SLAs competitively so that expected revenue for the computing utility is maximized and maintaining the operating conditions such that SLAs are satisfied with very high probability. In this paper, we show that inducting unreliable public resources into a computing utility enables more competitive SLAs while maintaining higher levels of run time compliances as well as maximizing profit. Our scheduling algorithms assume that idle cycles from public resources are available in plenty, therefore, the performance gains do not incur any additional financial cost. However, there is communication overhead when public resources from a wide area network is included. This overhead is kept to the minimum by enabling the scheduler work without any monitoring on the public resources.

A Cluster-Based Web System Providing Differentiated and Guaranteed Services

In a world where many users rely on the Web for up-to-date personal and business information and transactions, it is fundamental to build Web systems that allow service providers to differentiate user expectations with multi-class Service Level Agreements (SLAs). In this paper we focus on the server components of the Web, by implementing QoS principles in a Web-server cluster that is, an architecture composed by multiple servers and one front-end node called Web switch. We first propose a methodology to determine a set of confident SLAs in a real Web cluster for multiple classes of users and services. We then decide to implement at the Web switch level all mechanisms that transform a best-effort Web cluster into a QoS-enhanced system. We also compare three QoS-aware policies through experimental results in a real test-bed system. We show that the policy implementing all QoS principles allows a Web content provider to guarantee the contractual SLA targets also in severe load conditions. Other algorithms lacking some QoS principles cannot be used for respecting SLA constraints although they provide acceptable performance for some load and system conditions.