PBGC: Proxy Block-Based Garbage Collection for Index Structures in NAND Flash Memory

Seon Hwan KIM  Ju Hee CHOI  Jong Wook KWAK  

IEICE TRANSACTIONS on Information and Systems   Vol.E99-D   No.7   pp.1928-1932
Publication Date: 2016/07/01
Publicized: 2016/04/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.2015EDL8144
Type of Manuscript: LETTER
Category: Computer System
garbage collection,  NAND flash memory,  index structure,  proxy block,  

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In this letter, we propose a novel garbage collection technique for index structures based on flash memory systems, called Proxy Block-based Garbage Collection (PBGC). Many index structures have been proposed for flash memory systems. They exploit buffers and logs to resolve the update propagation problem, one of the a main cause of performance degradation of the index structures. However, these studies overlooked the fact that not only the record operation but also garbage collection induces the update propagation problem. The proposal, PBGC, exploits a proxy block and a block mapping table to solve the update propagation problem, which is caused by the changes in the page and block caused by garbage collection. Experiments show that PBGC decreased the execution time of garbage collection by up to 39%, compared with previous garbage collection techniques.