快閃記憶體檔案系統可靠度提升之多版本策略

Abstract

近年來，由於快閃記憶體晶片的可靠度降低，可靠度成為快閃記憶體檔案及儲存系統中一個關鍵的議題。在這篇論文中，基於恢復損壞檔案的需求，我們提出了一個多版本設計來有效地保持檔案中頁面版本的一致性。這個針對快閃記憶體檔案系統所設計的雙版本策略能夠在最小負擔下做版本控管。我們並且提出一個恢復機制來將損毀的檔案恢復到最新且一致的版本。我們將此設計加以延伸來管理多個資料版本，同時考慮到多階儲存單元快閃記憶體的寫入限制。我們以實驗證明這個多版本策略顯著地在有限的資源下改善了快閃記憶體的可靠度。

In recent years, reliability has become one critical issue in the designs of flashmemory file/storage systems, due to he growing unreliability of advanced flashmemory chips. In this paper, a version-based design is proposed to effectively and efficiently maintain the consistency among page versions of a file for potential recovery needs. In articular, a two-version one for a native file system is presented with the minimal overheads in version maintenance. A recovery scheme is then presented to restore a corrupted file back to the latest consistent version. The design is later extended to maintain multiple data versions with the considerations of the write constraints of multi-level-cell flash memory. It was shown that the proposed strategy could significantly improve the reliability of flash memory with limited management and space overheads.