Design of a hierarchical software-defined storage system for data-intensive multi-tenant cloud applications

Software-Defined Storage (SDS) is an evolving concept in which the management and provisioning of data storage is decoupled from the physical storage hardware. Data-intensive multi-tenant SaaS applications running on the public cloud could benefit from the concepts introduced by SDS by managing the allocation of tenant data from the tenant's perspective, taking custom tenant policies and preferences into account. In this paper, we propose the design of a scalable multi-tenant SDS system. In our approach, tenants are hierarchically clustered based on multiple scenario-specific characteristics. The storage elasticity component of the SDS system is responsible for the dynamic (re-) allocation of tenant data over the available storage resources. It invokes the Hierarchical Bin Packing algorithm introduced in this paper to determine an optimized distribution of tenant data based on the hierarchical tenant tree. We evaluate our system by means of two case studies based on real-life data sets. Experiments confirm that the Hierarchical Bin Packing algorithm achieves a good performance, with execution times below 100 ms to calculate the allocation for 1000 tenants in a worst-case scenario. Furthermore, our system achieves an average utilization of the storage resources close to the configured allocation factor, with reallocation of tenant data balanced over time

Network e-Volution

Modern society is a network society permeated by information technology (IT). As a result of innovations in IT, enormous amounts of information can be communicated to a larger number of recipients faster than ever before. The evolution of networks is heavily influenced by the extensive use of IT, which has enabled co-evolving advanced quantitative and qualitative forms of networking. Although several networks have been formed with the aim to reduce or deal with uncertainty through faster and broader access to information, it is in fact IT that has created new kinds of uncertainty. For instance, although digital information integration in supply chains has made production planning more robust, it has at the same time intensified mutual dependencies, thereby actually increasing the level of uncertainty. The aim of this working paper is to investigate the aspects of evolving networks and uncertainty in networks at the cutting edges of different types of networks and from the perspective of different layers defining these networks

Refinement and extension of the cloud decision support framework for application migration to the cloud

The maturity and dissemination of Cloud Computing across diverse business domains is leading to an increasing amount of migration projects with the goal to leverage the associated benefits for important legacy applications. However, the migration of applications to the cloud is a complex problem that entails various technical and organizational aspects. The existing Cloud Decision Support Framework has been a first step to provide decision makers with the means to find a suitable migration strategy. This master's thesis has refined the framework's underlying knowledge base by reviewing its decision points, decisions and their relations as well as outcomes. Based on this refinement, the framework has been extended by elaborating the relations between outcomes resulting in greater potential for decision support. In order to allow decision makers to derive migration strategies based on the framework in an interactive manner, a web application has been implemented. In a final step, an evaluation has been carried out comprising a validation of the knowledge base and, by means of a use case, a demonstration of the efficacy of the extended decision support framework

Rahmenwerk zur integrativen Gestaltung von Services: Modellgetriebene Servicebeschreibung

Die vorliegende Arbeit befasst sich mit der modellgetriebenen Servicebeschreibung, einem Ansatz zur integrativen Beschreibung bzw. Modellierung von Services. Ausgehend von der Prämisse, dass die Natur von Services nur schwer zu erfassen ist und eine Disziplinen-übergreifende Positiv-Definition nicht erreicht werden kann, soll mit dem Ansatz eine Syn-these bisher vorhandener Modellierungsansätze erfolgen. Das Ziel liegt dabei nicht in einem erneuten Versuch, ein vollständiges Modell zur Beschreibung von Services zu entwickeln, sondern vielmehr vorhandene Perspektiven so zu integrieren, dass ein vollständiges Bild als eine Art Mosaik entsteht. Den Kern der Arbeit bildet das Service Modeling Framework. Als Rahmenwerk umfasst es Anforderungen und Restriktionen für die Arbeit mit unter-schiedlichen Servicemodellen, definiert Methoden zur Integration und bietet Werkzeuge, mit deren Hilfe die darin enthaltenen Konzepte umgesetzt werden. Ziel der Konstruktion des Rahmenwerks ist es Nutzer in die Lage zu versetzen mittels mo-dellgetriebener Verfahren eine Zusammenführung von Modellen zu ermöglichen. Auf Basis einer fachlichen, nicht nur syntaktischen Beschreibung von Beziehungen zwischen Model-len und Modellelementen sollen Zusammenhänge modelliert werden, die einen Informati-onsaustausch zwischen Modellen realisieren. Dadurch werden Abhängigkeiten zwischen Modellen explizit formuliert oder aber die Entwicklung neuer Modelle auf Basis bereits bestehender Modelle vorangetrieben. Der Beitrag dieser Arbeit besteht in der Erarbeitung der notwendigen Konzepte und in der Bereitstellung geeigneter Verfahren sowie Werkzeugen zur Umsetzung. Insbesondere stellt diese Arbeit einen Metamodell-basierten Ansatz zur Verfügung, mit dem Modelle über ein Domänen-neutrales Basismetamodell zueinander in Beziehung gesetzt werden können. Zugehörige Werkzeuge, wie Editoren, zeigen eine prototypische Umsetzbarkeit

The interface between outsourcing and organisation controls in a large multinational technology organisation

This study examined employees’ view of the influence of intra and inter-organisational controls on their work. The findings highlighted the significance of time-based measurements in influencing the quality of solutions, and illustrated individuals’ use of creativity and negotiation and to bypass constraints experienced with internal controls