A log buffer-based flash translation layer using fully-associative sector translation

TLDR

Flash memory is widely used in mobile devices for its low power, nonvolatile storage, high performance, and portability, but its inability to overwrite data without a preceding erase operation degrades write performance, making log block buffer schemes the most effective FTL approach. The authors aim to enhance the log block buffer scheme by introducing FAST, a full associative sector translation method, to improve performance. FAST achieves this by employing fully-associative sector translations within a small number of log blocks, thereby increasing space utilization and reducing erase operations. Empirical results show that FAST improves log block space utilization and outperforms the conventional log block buffer scheme.

Abstract

Flash memory is being rapidly deployed as data storage for mobile devices such as PDAs, MP3 players, mobile phones, and digital cameras, mainly because of its low electronic power, nonvolatile storage, high performance, physical stability, and portability. One disadvantage of flash memory is that prewritten data cannot be dynamically overwritten. Before overwriting prewritten data, a time-consuming erase operation on the used blocks must precede, which significantly degrades the overall write performance of flash memory. In order to solve this “erase-before-write” problem, the flash memory controller can be integrated with a software module, called “flash translation layer (FTL). ).” Among many FTL schemes available, the log block buffer scheme is considered to be optimum. With this scheme, a small number of log blocks, a kind of write buffer, can improve the performance of write operations by reducing the number of erase operations. However, this scheme can suffer from low space utilization of log blocks. In this paper, we show that there is much room for performance improvement in the log buffer block scheme, and propose an enhanced log block buffer scheme, called FAST (full associative sector translation). Our FAST scheme improves the space utilization of log blocks using fully-associative sector translations for the log block sectors. We also show empirically that our FAST scheme outperforms the pure log block buffer scheme.