快閃記憶體空間回收效能提升:高效區塊選擇之設計

Performance Enhancement of Garbage Collection for Flash Storage Devices: An Efficient Victim Block Selection Design

曹哲維(Che-Wei Tsao)

指導教授 ： 高立人 ； 張原豪

國立臺北科技大學/電資學院/電腦與通訊研究所/碩士(2012年)

摘要

最近的研究發現，快閃記憶體所組成的儲存體裝置，使用時間一久掉速的問題就越來越嚴重，因此需要增強空間回收之效能在快閃記憶體儲存裝置，本篇論文在沒有顯著增加管理成本與沒有大幅更改快閃記憶體管理機制的情況下，提升空間回收之效能。提出一個高速區塊選擇之設計，在不用掃描所有區塊之使用狀態下，有效快速選擇適合被回收的區塊並且回收無效資料所占用的空間﹔同時，這一個設計可以簡單的辨識並且回收已經被檔案系統所刪除檔案所占用的空間。最後以一系列基於效能評估模擬之實驗來證明本論文所提出的方法可以在有限的系統資源的情況下大幅改善空間回收之效能。

關鍵字

快閃記憶體 ； 檔案系統 ； 儲存體

並列摘要

Motivated by the needs to enhance the performance of garbage collection in low-cost flash storage devices, this work attempts to achieve improved performance of garbage collection for reclaiming space of invalid data without substantially increasing management overheads and without abundantly modifying popular flash management designs. A victim block selection design is proposed to efficiently
identify the blocks for erases and reclaim the space of invalid data without extensively scanning flash memory for the status of data stored in the storage. At the same time, this design could also easily identify and reclaim the space released by file systems. A series of experiments based on benchmark traces demonstrates the significantly improved performance of garbage collection with limited system overheads.

並列關鍵字

Flash Memory ； File System ； Storage

參考文獻

[1] Mendel Rosenblum and John K. Ousterhout. The Design and Implementation of a Log-Structured File System. ACM Trans. on Computer Systems 10(1), February 1992, pp. 26-52.

[2] Chiang, M., Lee, P.C.H., Chang, R., 1999. Cleaning algorithms in mobile computers using flash memory. Journal of Systems and Software. Volume 48 Issue 3, Nov. 1, 1999, pp. 213 - 231

[3] Sai Krishna Mylavarapu, Siddharth Choudhuri, Aviral Shrivastava, Jongeun Lee, Tony Givargis. FSAF: File system aware flash translation layer for NAND Flash Memories. DATE conference 2009, pp. 399-404

[6] Atsuo Kawaguchi, Shingo Nishioka, and Hiroshi Motoda. A flash-memory based file system. Proceeding TCON'95 Proceedings of the USENIX 1995 Technical Conference Proceedings, Pages 13-13

[4] AT Attachment 8 - ATA/ATAPI Command Set (ATA8-ACS)