CAREER: From Storm Clouds to EverClouds: Heading Off Long-Term Cloud Computing Risks

云计算模式无论从经济和管理的角度来看多么吸引人，但在太多的关键基础设施“迁移到云之前，应该理解它带来的风险。“虽然隐私和信息安全风险是众所周知的，但云计算可能会带来其他长期风险，这些风险既没有得到广泛认识，也没有得到解决。 EverCloud是一种新型的云计算模型，它探索并尝试减轻这些风险。首先，云加剧了定时侧通道的安全风险，而当前的方法无法在不破坏云商业模式的情况下解决这些风险。 EverCloud引入了定时信息流控制（Timing Information Flow Control，TIFC）模型，提供了一个工具来推理和限制定时通道，尽管有细粒度的硬件资源复用。其次，云服务构建在另一个之上，存在隐藏的交互风险，可能导致不可预测的不稳定或“崩溃”，以及资源相互依赖性，破坏服务的故障恢复能力。 EverCloud采用标签技术来强制执行反应式云计算的稳定性约束，并确保云硬件基础设施供应的独立性。第三，云加剧了数字保存的挑战，因为除了云应用程序的提供商之外，没有人可以存档应用程序及其数据的“工作”副本。 EverCloud使任何利益相关者（例如，客户、库管理员）创建并独立保存云应用程序的全功能“快照”，同时通过利益相关者之间按比例分摊成本来降低保存的计算、存储和带宽成本。通过探索这些可能的云计算风险和潜在的解决方案，EverCloud可以提高云计算的安全性、鲁棒性、和可预测性的云计算系统，在其中云计算越来越多地使用的许多领域。

The cloud computing model, however appealing from economic and management perspectives, brings risks that should be understood before too much critical infrastructure "moves to the cloud." While the privacy and information security risks are well-known, cloud computing may bring other long-term risks that are neither widely recognized nor addressed. EverCloud is a novel cloud computing model that explores and attempts to mitigate these risks.First, clouds exacerbate security risks from timing side-channels, which current approaches cannot address without undermining the cloud business model. EverCloud introduces a Timing Information Flow Control (TIFC) model, providing a tool to reason about and limit timing channels despite fine-grained hardware resource multiplexing.Second, cloud services built atop one another risk hidden interactions that might lead to unpredictable instabilities or "meltdowns," as well as resource interdependencies that undermine a service's resilience to failure. EverCloud adapts labeling techniques to enforce stability constraints on reactive cloud computations, and to ensure independence in the provisioning of cloud hardware infrastructure.Third, clouds exacerbate digital preservation challenges, because no one but a cloud application's provider can archive a "working" copy of the application and its data. EverCloud enables any stakeholder (e.g., customer, librarian) to create and independently preserve fully-functional "snapshots" of cloud applications, while mitigating the computing, storage, and bandwidth costs of preservation via proportionate cost-sharing among stakeholders.By exploring these possible cloud computing risks and potential solutions, EverCloud may increase the security, robustness, and predictability of cloud computing systems throughout the many areas in which cloud computing is increasingly used.