Weijia Song

Supercloud: Opportunities and Challenges

Infrastructure as a Service (IaaS) clouds couple applications tightly with the underlying infrastructures and services. This vendor lock-in problem forces users to apply ad-hoc deployment strategies in order to tolerate cloud failures, and limits the ability of doing virtual machine (VM) migration and resource scaling across different clouds. This paper presents the Supercloud, a cloud service comprising resources obtained from several diverse IaaS cloud providers, and discusses opportunities, limitations, and future research directions. Currently, the Supercloud has been deployed using resources from several major cloud providers, including Amazon EC2, Rackspace, HP Cloud, and some private clouds. VMs run in a virtual network and can be migrated seamlessly across different clouds, with different hypervisors and device models. Using case studies we demonstrate that, being able to deploy applications to more regions and granting more control to end-users, the Supercloud can reduce latency and cost compared to the underlying cloud providers.

Follow the Sun through the Clouds: Application Migration for Geographically Shifting Workloads

Global cloud services have to respond to workloads that shift geographically as a function of time-of-day or in response to special events. While many such services have support for adding nodes in one region and removing nodes in another, we demonstrate that such mechanisms can lead to significant performance degradation. Yet other services do not support application-level migration at all. Live VM migration between availability zones or even across cloud providers would be ideal, but cloud providers do not support this flexible mechanism. This paper presents the Supercloud, a uniform cloud service that supports live VM migration between data centers of all major public cloud providers. The Supercloud also provides a scheduler that automatically determines when and where to move VMs for optimal performance. We demonstrate that live VM migration can support shifting workloads effectively, with low downtimes and transparently to both services and their clients. The Supercloud also addresses challenges for supporting cross-cloud storage and networking.

Smart spot instances for the supercloud

In this paper, we explore the use of live VM migration to take advantage of spot markets such as provided by Amazon and Google. These markets provide an exciting low cost alternative to regular VM instances, but the threats of price spikes and premature termination severely limit their usability. Migration can address these threats: spot market instances facing price hikes or termination can migrate to other instance types, including regular ones. Reliability can be further improved by replication. In this paper we investigate various design options and present some preliminary results of experiments with dynamic programming techniques, both using simulation and using a realistic deployment. We find that in unstable markets we can achieve significant savings at low overhead and while maintaining good reliability.

Supercloud: A Library Cloud for Exploiting Cloud Diversity

Infrastructure-as-a-Service (IaaS) cloud providers hide available interfaces for virtual machine (VM) placement and migration, CPU capping, memory ballooning, page sharing, and I/O throttling, limiting the ways in which applications can optimally configure resources or respond to dynamically shifting workloads. Given these interfaces, applications could migrate VMs in response to diurnal workloads or changing prices, adjust resources in response to load changes, and so on. This article proposes a new abstraction that we call a Library Cloud and that allows users to customize the diverse available cloud resources to best serve their applications. We built a prototype of a Library Cloud that we call the Supercloud. The Supercloud encapsulates applications in a virtual cloud under users’ full control and can incorporate one or more availability zones within a cloud provider or across different providers. The Supercloud provides virtual machine, storage, and networking complete with a full set of management operations, allowing applications to optimize performance. In this article, we demonstrate various innovations enabled by the Library Cloud.