Hybrid FTL Plans

7 Apr

Hybrid FTL plans to build a page-level mapping LBA. This table resides in the SRAM, Bast limit the replacement block in order to maintain sufficiently small, the total number (also referred to as the log block). Obviously, the read performance is better than NFTL-1, because the SRAM is several orders of magnitude faster than flash memory. Bast random overwrite mode does not work, however, this may be due to the jitter problem in a block. Since each replacement block can accommodate only page a logical block, bast can easily run a free replacement block is mandatory recycling replacement block has not been filled. Therefore, the utilization rate of bast replacement block is a low theoretical and experimental.

In order to solve this block jitter problems, another hybrid FTL, called FAST (fully associative sector translation) proposed. The other extreme allows quick access to the update log block from any data block. Fast, delay garbage collection as much as possible, for the recovery of the system-wide delay a single log block may turn out to be longer than the phloem, because the combination of the log block is only limited by the number of pages in a block . The correlation between the log block is defined as the number of different data block, log block in its latest position of the page. Correlation between the higher the log block, more expensive it toreclaim. In order to improve the proportion of part and switch combination, fast Reserve sequence log block execution is continuously updated. This optimization is limited, because the modern multi-process environment is often interrupted by random write and sequential write, sequential write.

In the ensuing years, the researchers trying to find some balance between the middle of the proposed log block utilization and reclamation overhead. There are some typical representative of such super-block FTL, SAST (translate SetAssociative sector) [26] LAST (locality-aware sector translation), A-SAST (adaptive SAST these two super-block FTL, and SAST share (most) K log N blocks of data block. the superblock FTL keep the page-level map in the spare area superblock, SAST to the limit of the number of log blocks and kept in the SRAM page-level map. spare area size limit superblock FTL up to three spare area to search to find a requested page.


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