WAFLASH: Taming Unaligned Writes in Solid-State Disks
WAFLASH: Taming Unaligned Writes in Solid-State Disks
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DOI：
10.1109/nas55553.2022.9925375
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发表时间：
2022-10
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影响因子：
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通讯作者：
Shuibing He;M. Myers;Xuehao Duan;Keegan Sanchez;Xuechen Zhang
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作者：
Shuibing He;M. Myers;Xuehao Duan;Keegan Sanchez;Xuechen Zhang
从数据中心的高端服务器到云计算边缘的移动的计算机，基于NAND闪存的固态硬盘（SSD）正在取代各种存储系统中的硬盘驱动器（HDD）。由于SSD的架构性质，性能敏感型应用程序可能会在SSD上生成大量未对齐的写入，这可能导致许多问题，包括芯片拥塞、子请求阻塞、芯片负载不平衡和写入空间放大。本文提出了一种写入对齐的闪存驱动器（WAFLASH），全面和显着地消除了固态磁盘中的非对齐写入的副作用。我们使用三个关键技术：（1）在写缓冲器中将完全填充的页面的逐出优先于部分填充的页面，（2）在闪存中存储由未对准的写/重写请求的多版本数据，以及（3）在物理页中压缩多个小的部分填充的页以避免写入放大并减少关键I/O中的附加读取的数量。我们在VSSIM和Cosmos+ OpenSSD中实现了WAFLASH。结果表明，WAFLASH将I/O吞吐量提高了125%。
Ahstract-NAND-flash based solid-state disks (SSDs) are replacing the hard-disk drives (HDDs) in various storage systems from high-end servers in data centers to mobile computers on the edges of cloud computing. Due to the architectural nature of SSDs, performance-sensitive applications may generate a large number of unaligned writes on SSDs, which can cause many issues including chip congestion, sub-request blocking, chip load imbalance, and write space amplification. This paper presents a Write-Aligned FLASH drive (WAFLASH) that comprehensively and significantly alleviates the side-effects of unaligned writes in solid-state disks. We utilize three key techniques: (1) prioritizing eviction of fully-filled pages over partially-filled pages in write buffers, (2) storing multi-version data requested by unaligned writes/overwrites in flash memory, and (3) compacting multiple small partially-filled pages in a physical page to circumvent write amplification and reduce the number of additional reads in the critical I/O path. We implement WAFLASH in VSSIM and Cosmos+ OpenSSD. The results show WAFLASH increases I/O throughput by up to 125% with the Filebench benchmark.