CNS Core: Small: CPR for Flash-Based Storage Systems

基于闪存的固态驱动器（SSD）的底层硬件变得越来越不可靠，并且当前最先进的方法实现性能牺牲技术以防止数据丢失。随着存储老化，此问题会加剧，从而导致性能不可预测性并使性能异常检测变得困难。在当前的容量不变接口中，存储设备在其整个生命周期中导出固定容量，SSD别无选择，只能在磨损时以性能换取可靠性。本项目从整体的角度对现有的存储接口进行重新思考，在容量、性能和可靠性（CPR）之间进行权衡，设计灵活的容量可变接口，使SSD在保持性能的同时适度减少导出的块数。本项目涉及三个研究方向。第一个推力是通过构建SSD老化框架来量化错误引起的性能下降。第二个重点则是建立一个能力可变的系统，并展示这种方法的有效性。最后，该项目研究了如何在SSD的异构聚合中扩展容量差异。该项目预计将对存储行业产生重大影响，因为它解决的问题既及时，如果不加以控制，可能会变得更糟。容量可变的存储系统可以使存储系统的维护和配置更容易，该项目将有助于教育学生跨层优化和整体设计思维的价值和重要性。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The underlying hardware for flash memory-based solid-state drive (SSD) is becoming increasingly unreliable, and the current state-of-the-art approaches implement performance-sacrificing techniques to prevent data loss. This problem is exacerbated as the storage ages, causing performance unpredictability and making performance anomaly detection difficult. In the current capacity-invariant interface where the storage device exports a fixed capacity throughout its lifetime, an SSD has no other choice but to trade performance for reliability as it wears out. This project rethinks the existing storage interface from a holistic perspective by exploiting tradeoffs among capacity, performance, and reliability (CPR) and designing a flexible capacity-variant interface that allows the SSD to maintain performance while it gracefully reduces the number of exported blocks.The project involves three research thrusts. The first thrust is to quantify the error-induced performance degradation by building an SSD aging framework. The second thrust then builds a capacity-variant system and demonstrates the effectiveness of such an approach. Lastly, the project studies how capacity-variance can be extended across a heterogeneous aggregation of SSDs. The project is expected to have a major impact in the storage industry, as the problem it addresses is both timely and likely to get worse if left unchecked. A capacity-variant storage system can make storage system maintenance and provisioning easier, and this project will help educate students on the value and importance of cross-layer optimization and holistic design thinking.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.