Better duplicate elimination performance causes higher fragmentation which leads to degraded restore performance. As a result, restore performance needs to be optimized either through strengthening locality by selective rewriting and/or making the best use of the limited available memory through cache optimization. In this paper, we explore SACRO, SSD Assitsted Chunk Caching for Restore Optimization. It avoids the need to repetitively access chunk containers in disk by using SSD (Solid State Drives) as a secondary chunk cache. An FRT (Future Reference Table) is constructed from the recipe of a backup stream and a Future Reference Count entry in the FRT is utilized to assign priorities to chunks as they are accessed during restoration. These priority values coupled with access distances are used to decide to cache a chunk either in memory or the SSD. The restore performance of SACRO is shown to significantly outperform other restoring approaches which utilize chunk caching. For one dataset, at 4 MB cache size and 4 MB Look Ahead Window size its restore factor is 3.5 MB/container_access while ALACC and LRU record 3.4 MB/container_access and 0.9 MB/container_access respectively. Moreover, SACRO can be integrated to already existing deduplication systems with very limited amount of modification done on the deduplication system.

中文翻译：

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SACRO：用于恢复优化的固态硬盘辅助块缓存

更好的重复消除性能会导致更高的碎片，从而导致恢复性能下降。因此，需要通过选择性重写来加强局部性和/或通过缓存优化充分利用有限的可用内存来优化恢复性能。在本文中，我们探讨了 SACRO、S SD A ssitsted Chunk C aching for Restore O优化。它通过使用 SSD（固态硬盘）作为辅助块缓存，避免了重复访问磁盘中的块容器。FRT（未来参考表）是根据备份流的配方构建的，并且 FRT 中的未来参考计数条目用于在恢复期间访问块时为块分配优先级。这些优先级值与访问距离相结合，用于决定将块缓存在内存中还是 SSD 中。SACRO 的恢复性能明显优于其他利用块缓存的恢复方法。对于一个数据集，在 4 MB 缓存大小和 4 MB 预读窗口大小下，其恢复因子为 3.5 MB/container_access，而 ALACC 和 LRU 记录分别为 3.4 MB/container_access 和 0.9 MB/container_access。而且，