CoPA：克服基于I/O的STT-MRAM缓冲区中的保留故障的冷页唤醒
CoPA: Cold Page Awakening to Overcome Retention Failures in STT-MRAM Based I/O Buffers
摘要：
性能和可靠性是数据存储系统设计中的两个重要因素。为了实现更高的性能，最近存储系统设计者使用基于DRAM的缓冲器。DRAM的易失性带来了数据丢失的可能性，因此通常将主存储器的一部分用作日志区，以便在停电的情况下能够恢复未刷新的数据页。此外，周期性地将缓冲的数据页刷新到主存储器是保持高水平可靠性的常见机制，这导致存储写入业务的增加。为了解决这个缺点，最近的研究提供了一个小的NVM作为持久性日志区（PJA）以及DRAM作为一种有效的方法，称为NVM支持的缓冲区（NVB缓冲区）。这种方法旨在解决DRAM对电源故障的脆弱性，同时减少存储写入流量。在本文中，我们使用新兴技术中最有前途的PJA技术，这是STT-MRAM，以满足PJA的要求（高耐久性，非易失性和DRAM般的延迟）。然而，STT-MRAM面临主要的可靠性挑战，即，保持故障、读取干扰和写入故障。在本文中，我们首先表明，保留失败是在NVB缓冲区的错误的主要来源，因为它遭受长期和不可预测的页面空闲间隔。然后，我们提出了一种新的NVB缓冲区管理方案，命名为，冷页唤醒（CoPA），可预见地减少PJA页面的空闲时间。为此，CoPA采用远程刷新定期覆盖易受攻击的PJA页面内容，通过使用它们的副本在基于DRAM的缓冲区。我们比较了基于物理日志的几个工作负载的CoPA与最先进的方案。我们的评估表明，采用CoPA导致三个数量级的故障率降低，性能下降（1.1%）和内存开销（1.2%）可以忽略不计。
英文摘要：
Performance and reliability are two prominent factors in the design of data storage systems. To achieve higher performance, recently storage system designers use DRAM-based buffers. The volatility of DRAM brings up the possibility of data loss, so a part of the main storage is conventionally used as the journal area to be able of recovering unflushed data pages in the case of power failure. Moreover, periodically flushing buffered data pages to the main storage is a common mechanism to preserve a high level of reliability, which leads to an increase in storage write traffic. To address this shortcoming, recent studies offer a small NVM as the Persistent Journal Area (PJA) along with DRAM as an efficient approach, named NVM-Backed Buffer (NVB-Buffer). This approach aims to address DRAM vulnerability against power failure while reducing storage write traffic. In this paper, we use the most promising technologies for PJA among the emerging technologies, which is STT-MRAM to meet the requirements of PJA (high endurance, non-volatility, and DRAM-like latency). However, STT-MRAM faces major reliability challenges, i.e. Retention Failure, Read Disturbance, and Write Failure. In this paper, we first show that retention failure is the dominant source of errors in NVB-Buffers as it suffers from long and unpredictable page idle intervals. Then, we propose a novel NVB-Buffer management scheme, named, Cold Page Awakening (CoPA), which predictably reduces the idle time of PJA pages. To this aim, CoPA employs Distant Refreshing to periodically overwrite the vulnerable PJA page contents by using their replica in DRAM-based buffer. We compare CoPA with the state-of-the-art schemes over several workloads based on physical journaling. Our evaluations show that employing CoPA leads to three orders of magnitude lower failure rate with negligible performance degradation (1.1%) and memory overhead (1.2%).
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
