Title
TBF: A memory-efficient replacement policy for flash-based caches
Abstract
The performance and capacity characteristics of flash storage make it attractive to use as a cache. Recency-based cache replacement policies rely on an in-memory full index, typically a B-tree or a hash table, that maps each object to its recency information. Even though the recency information itself may take very little space, the full index for a cache holding N keys requires at least log N bits per key. This metadata overhead is undesirably high when used for very large flash-based caches, such as key-value stores with billions of objects. To solve this problem, we propose a new RAM-frugal cache replacement policy that approximates the least-recently-used (LRU) policy. It uses two in-memory Bloom sub-filters (TBF) for maintaining the recency information and leverages an on-flash key-value store to cache objects. TBF requires only one byte of RAM per cached object, making it suitable for implementing very large flash-based caches. We evaluate TBF through simulation on traces from several block stores and key-value stores, as well as evaluate it using the Yahoo! Cloud Serving Benchmark in a real system implementation. Evaluation results show that TBF achieves cache hit rate and operations per second comparable to those of LRU in spite of its much smaller memory requirements.
Year
DOI
Venue
2013
10.1109/ICDE.2013.6544902
ICDE
Keywords
DocType
Citations 
new RAM-frugal cache replacement,full index,large flash-based cache,Recency-based cache replacement policy,N key,key-value store,memory-efficient replacement policy,cache hit rate,recency information,cached object,on-flash key-value store
Conference
3
PageRank 
References 
Authors
0.40
0
4
Name
Order
Citations
PageRank
Biplob Debnath135719.47
Cristian Ungureanu243625.80
Akshat Aranya313510.11
Stephen Rago4583.63