A Hash Table, also known as a hash map, is a data structure that implements an associative array abstract data type. It uses a hash function to map keys to indexes in an array, allowing for efficient storage and retrieval of data. Hash tables are widely used in computer science for their fast average-case time complexity for basic operations, such as insertion, deletion, and lookup.

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Austere Flash Caching with Deduplication and Compression

Austere Flash Caching with Deduplication and Compression Modern storage systems leverage flash caching to boost I/O performance, and enhancing the space efficiency and endurance of flash caching remains a critical yet challenging issue in the face of ever-growing data-intensive workloads. Deduplication and compression are promising data reduction techniques for storage and I/O savings via the removal of duplicate content, yet they also incur substantial memory overhead for index management. We propose AustereCache, a new flash caching design that aims for memory-efficient indexing, while preserving the data reduction benefits of deduplication and compression. AustereCache emphasizes austere cache management and proposes different core techniques for efficient data organization and cache replacement, so as to eliminate as much indexing metadata as possible and make lightweight in-memory index structures viable. Trace-driven experiments show that our AustereCache prototype saves 69.9-97.0% of memory usage compared to the state-of-the-art flash caching design that supports deduplication and compression, while maintaining comparable read hit ratios and write reduction ratios and achieving high I/O throughput.