LoopDelta: Embedding Locality-aware Opportunistic Delta Compression in Inline Deduplication for Highly Efficient Data Reduction
LoopDelta: Embedding Locality-aware Opportunistic Delta Compression in Inline Deduplication for Highly Efficient Data Reduction
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发表时间：
2023
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通讯作者：
Yucheng Zhang;Hong Jiang;D. Feng;Nan Jiang;Taorong Qiu;Wei Huang
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作者：
Yucheng Zhang;Hong Jiang;D. Feng;Nan Jiang;Taorong Qiu;Wei Huang
作为重复数据删除的补充，增量压缩通过压缩相对于相似块（基本块）的非重复数据块来进一步减少数据量。然而，现有的用于备份存储的重复数据删除后增量压缩方法要么存在许多检测到的块之间相似性较低的问题，要么会遗漏一些潜在的相似块，要么由于读取基本块需要额外的I/ o，或者为备份系统增加额外的业务中断操作，从而导致吞吐量较低（备份和恢复）。在本文中，我们提出了LoopDelta以一种非侵入式的方式在重复数据删除中增强嵌入增量压缩方案来解决上述问题。增强的增量压缩方案结合了四个关键技术：(1)基于双位置的相似度跟踪，利用逻辑和物理位置来检测潜在的相似块；(2)位置感知预取，预取基本块，以避免在写路径上读取基本块的额外I/ o；(3)缓存感知过滤器，以避免在读路径上读取基本块的额外I/ o；(4)反向增量压缩，通过重写旨在提高恢复性能的技术，对数据块执行增量压缩，否则这些数据块将被禁止作为基本块。实验结果表明，LoopDelta在重复数据删除的基础上将压缩比提高了1.24 ~ 10.97倍，而对备份吞吐量没有明显影响，恢复性能提高了1.2 ~ 3.57倍。
As a complement to data deduplication, delta compression further reduces the data volume by compressing non-duplicate data chunks relative to their similar chunks (base chunks). However, existing post-deduplication delta compression approaches for backup storage either suffer from the low similarity between many detected chunks or miss some potential similar chunks, or suffer from low (backup and restore) throughput due to extra I/Os for reading base chunks or add additional service-disruptive operations to backup systems. In this paper, we propose LoopDelta to address the above-mentioned problems by an enhanced embedding delta compression scheme in deduplication in a non-intrusive way. The enhanced delta compression scheme combines four key techniques: (1) dual-locality-based similarity tracking to detect potential similar chunks by exploiting both logical and physical locality, (2) locality-aware prefetching to prefetch base chunks to avoid extra I/Os for reading base chunks on the write path, (3) cache-aware filter to avoid extra I/Os for base chunks on the read path, and (4) inversed delta compression to perform delta compression for data chunks that are otherwise forbidden to serve as base chunks by rewriting techniques designed to improve restore performance. Experimental results indicate that LoopDelta increases the compression ratio by 1.24 ∼ 10.97 times on top of deduplication, without notably affecting the backup throughput, and it improves the restore performance by 1.2 ∼ 3.57 times.