Cloud Index Tracking: Enabling Predictable Costs in Cloud Spot Markets

Cloud spot markets rent VMs for a variable price that is typically much lower than the price of on-demand VMs, which makes them attractive for a wide range of large-scale applications. However, applications that run on spot VMs suffer from cost uncertainty, since spot prices fluctuate, in part, based on supply, demand, or both. The difficulty in predicting spot prices affects users and applications: the former cannot effectively plan their IT expenditures, while the latter cannot infer the availability and performance of spot VMs, which are a function of their variable price. To address the problem, we use properties of cloud infrastructure and workloads to show that prices become more stable and predictable as they are aggregated together. We leverage this observation to define an aggregate index price for spot VMs that serves as a reference for what users should expect to pay. We show that, even when the spot prices for individual VMs are volatile, the index price remains stable and predictable. We then introduce cloud index tracking: a migration policy that tracks the index price to ensure applications running on spot VMs incur a predictable cost by migrating to a new spot VM if the current VM's price significantly deviates from the index price.Comment: ACM Symposium on Cloud Computing 201

Disaggregated Memory at the Edge

This paper describes how to augment techniques such as Distributed Shared Memory with recent trends on disaggregated Non Volatile Memory in the data centre so that the combination can be used in an edge environment with potentially volatile and mobile resources. This article identifies the main advantages and challenges, and offers an architectural evolution to incorporate recent research trends into production-ready disaggregated edges. We also present two prototypes showing the feasibility of this proposal

Envisioning SLO-driven Service Selection in Multi-cloud Applications

The current large selection of cloud instances that are functionally equivalent makes selecting the right cloud service a challenging decision. We envision a model driven engineering (MDE) approach to raise the level of abstraction for cloud service selection. One way to achieve this is through a domain specific language (DSL) for modelling the service level objectives (SLOs) and a brokerage system that utilises the SLO model to select services. However, this demands an understanding of the provider SLAs and the capabilities of the current cloud modelling languages (CMLs). This paper investigates the state-of-the-art for SLO support in both cloud providers SLAs and CMLs in order to identify the gaps for SLO support. We then outline research directions towards achieving the MDE-based cloud brokerage

Julkisen pilven palveluihin siirtyminen

Julkisen pilven palvelut ovat kasvaneet voimakkaasti viimeisen kymmenen vuoden aikana. Monet organisaatiot pyrkivät ulkoistamaan IT:n tuottamisen pilvipalveluntarjoajalle ja tavoittelevat kustannussäästöjä ostamalla vain oikean määrän IT-palveluita sen sijaan, että investoitaisiin itse omistettuun IT-infrastruktuuriin. Tässä kandidaatintyössä tutkitaan kirjallisuustutkimuksen keinoin aiemman tutkimuskirjallisuuden perusteella millaisia edellytyksiä ja haasteita julkisen pilven palveluihin siirtymiseen liittyy. Samoin tarkastellaan, millaisia hyötyjä on tavoiteltu ja mihin on päästy. Tavoitellut kustannussäästöt eivät aina varsinkaan isompien organisaatioiden tapauksessa välttämättä realisoidu, mutta julkisen pilven palveluiden käyttöönotto tuo organisaation IT:hen uutta joustavuutta ja helpottaa uusien teknologioiden testaamista.Public cloud services have been growing fast for the last 10 years. Many organizations are outsourcing their IT production to cloud service providers and are aiming at cost savings by buying the right amount of IT as service instead of investing in an on-premise IT-infrastructure. This bachelor's thesis is a literature review researching the prerequisites and challenges of migrating to using public cloud based services. The benefits organizations are aiming at and the benefits they manage to achieve are also looked at. A key category of challenges in migrating to using public cloud based services are different types of security related challenges. The cost savings organizations aim at do not always materialize, especially for larger organizations. Nonetheless migrating to public cloud based services can introduce new flexibility to an organization's IT and makes testing new technologies easier

SLO-ML:A Language for Service Level Objective Modelling in Multi-cloud applications

Cloud modelling languages (CMLs) are designed to assist customers in tackling the diversity of services in the current cloud market. While many CMLs have been proposed in the literature, they lack practical support for automating the selection of services based on the specific service level objectives of a customer's application. We put forward SLO-ML, a novel and generative CML to capture service level requirements. Subsequently, SLO-ML selects the services to honour the customer's requirements and generates the deployment code appropriate to these services. We present the architectural design of SLO-ML and the associated broker that realises the deployment operations. We evaluate SLO-ML using an experimental case study with a group of researchers and developers using a real-world cloud application. We also assess SLO-ML's overheads through empirical scalability tests. We express the promises of SLO-ML in terms of gained productivity and experienced usability, and we highlight its limitations by analysing it as application requirements grow

Research challenges in nextgen service orchestration

Fog/edge computing, function as a service, and programmable infrastructures, like software-defined networking or network function virtualisation, are becoming ubiquitously used in modern Information Technology infrastructures. These technologies change the characteristics and capabilities of the underlying computational substrate where services run (e.g. higher volatility, scarcer computational power, or programmability). As a consequence, the nature of the services that can be run on them changes too (smaller codebases, more fragmented state, etc.). These changes bring new requirements for service orchestrators, which need to evolve so as to support new scenarios where a close interaction between service and infrastructure becomes essential to deliver a seamless user experience. Here, we present the challenges brought forward by this new breed of technologies and where current orchestration techniques stand with regards to the new challenges. We also present a set of promising technologies that can help tame this brave new world