CSR: Medium: Rethinking Distributed SSD Storage Systems

CSR：中：重新思考分布式 SSD 存储系统

• 批准号: 1763546
• 负责人: Michael Freedman
• 金额: $ 100万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1763546&HistoricalAwards=false
• 关键词: CSR; Medium; Rethinking; Distributed; SSD

Modern storage technologies, such as solid-state disks (SSDs), have increased their capacity by increasing density: representing more digital bits in the same physical media. To do so, their margin of error for representing data has shrunk, and the resulting bit error rate has risen. While disks employ error correcting codes to mask such bit errors, these error rates rise as disk blocks age, by being (over)written, and eventually the disk fails. Thus, as density has risen, disks' expected lifetimes have plunged. This research rethinks how to build scalable and cost-effective storage through a cross-layer design to the storage stack.For most datacenter applications, objects are already replicated between multiple devices, and this application-layer redundancy can be leveraged for increased reliability. This research thus explores a new approach for end-to-end reliability for SSD storage systems: datacenter flash devices should be far less reliable and push error visibility and correction up to the distributed application layer. The design challenges and implications of providing such a holistic, cross-layer approach are explored through three research thrusts: at the individual disk layer, at the local file system, and at the distributed storage system layer.By extending the lifecycle of disks by several orders of magnitude, this research has the potential for the adoption of new SSD storage technologies, significant cost savings, and enabling new applications to use SSDs. Due to the plunging lifecycles of newer generations of SSD technologies, large datacenter applications have been unable to integrate these new generations in a number of scenarios (e.g., workloads with heavy write rates, including databases and caches). Given this research's potential for orders of magnitude of reliability improvements, it provides a potential path out from this reliability cliff of the hardware.Code, data, and results relating to this research will be made available via a git repository, hosted publicly at https://github.com/princeton-sns/crosslayer-storage/. Materials will be available throughout the Award term and at least five years following it.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.

现代存储技术，例如固态磁盘（SSD），通过增加密度来增加容量：在相同的物理介质中代表更多的数字位。 为此，它们表示数据的误差幅度已经缩小，并且导致误码率上升。 虽然磁盘使用纠错码来掩盖此类位错误，但随着磁盘块老化（通过被（覆盖）写入），这些错误率会上升，并最终导致磁盘出现故障。 因此，随着密度的增加，磁盘的预期寿命也随之缩短。 这项研究重新思考了如何通过存储堆栈的跨层设计来构建可扩展且经济高效的存储。对于大多数数据中心应用程序来说，对象已经在多个设备之间复制，可以利用这种应用程序层冗余来提高可靠性。 因此，本研究探索了一种实现 SSD 存储系统端到端可靠性的新方法：数据中心闪存设备的可靠性应该低得多，并将错误可见性和纠正推送到分布式应用程序层。 通过三个研究重点探讨了提供这种整体跨层方法的设计挑战和含义：在单个磁盘层、本地文件系统和分布式存储系统层。数量级上，这项研究有可能采用新的 SSD 存储技术，显着节省成本，并使新应用程序能够使用 SSD。 由于新一代 SSD 技术的生命周期急剧缩短，大型数据中心应用程序无法在许多场景中集成这些新一代 SSD（例如，写入速率较高的工作负载，包括数据库和缓存）。 鉴于这项研究有可能实现数个数量级的可靠性改进，它提供了摆脱硬件可靠性悬崖的潜在途径。与这项研究相关的代码、数据和结果将通过 git 存储库提供，该存储库公开托管在 https： //github.com/princeton-sns/crosslayer-storage/。 材料将在整个奖项期限内以及之后至少五年内提供。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Who's Afraid of Uncorrectable Bit Errors? Online Recovery of Flash Errors with Distributed Redundancy

• 发表时间: 2019
• 期刊: Advanced Energy Materials
• 影响因子: 27.8
• 作者: Amy Tai;Andrew Kryczka;Shobhit O. Kanaujia;K. Jamieson;M. Freedman;Asaf Cidon