CAREER: Building Virtual Devices with QoS Assurance in a Consolidated Storage Infrastructure

在存储资源的使用和管理中，一个不断增长的不可避免的趋势是将分布式存储整合到一个大型数据中心中，以降低快速增长的管理成本并提高资源利用率。尽管其引人注目的优势和多年的研究和产品开发的努力，在把这个有前途的技术变成现实的一个关键挑战仍然有待解决，这是I/O服务（QoS）的质量不能方便地提出和有效地保证谁的用户谁外包他们的专用存储到共享系统。为此，性能接口或所需服务质量的规范必须能够允许不同的用户集合容易地将他们的I/O QoS要求中的每一个与他们各自的应用性能相关联，并且使有效的系统实现能够满足QoS要求。目前，QoS要求通常以服务级别协议（SLA）的形式提出，以限制I/O请求的延迟和吞吐量。SLA不适用于从应用服务器到存储服务器的I/O请求，因为用户在使用性能接口时会遇到困难，而且SLA度量可能会误导资源分配，因为SLA度量不能一致地反映用户的资源需求。为了解决这个关键问题，研究者将制定一份参考文件，作为性能接口的存储设备（或虚拟存储设备），并将基于该接口实现整合存储服务。以这种方式，保证用户接收到其质量至少与参考系统上的质量一样好的I/O服务，而不管数据访问模式的变化和瞬时改变。该研究项目旨在消除用户和系统管理员沟通I/O性能要求的重大障碍，并为存储整合技术的广泛接受铺平道路。

A growing and inevitable trend in the use and management of storage resources is the consolidation of distributed storage into a large data center to reduce the rapidly growing administration cost and to improve resource utilization. Despite its compelling advantages and years of efforts on research and product development, a critical challenge in turning this promising technology into reality remains to be addressed, which is that the quality of the I/O services (QoS) cannot be conveniently presented and efficiently guaranteed for users who outsource their dedicated storages to the shared system. To this end, a performance interface, or specification of required service quality, must be able to allow a diverse set of users to easily relate each of their I/O QoS requirements to their respective application performance and enable efficient system implementation to meet the QoS requirements. Currently, the QoS requirements are usually presented in the form of service-level agreements (SLAs) to bound latency and throughput of I/O requests. SLA is not suitable for I/O requests from application servers to storage servers because users have difficulties in using the performance interface and resources allocation can be misguided by the SLA measures, which do not consistently reflect users' resource demands.To address this critical issue, the investigator will develop a reference (or virtual) storage device as performance interface and will implement consolidated storage service based on the interface. In this way, a user is guaranteed to receive an I/O service whose quality is at least as good as that on the reference system regardless of variations and instantaneous changes of data access patterns. The research project aims to remove the significant barrier for users and system administrators to communicate I/O performance requirements and pave the road to wide acceptance of the storage consolidation technology.