2 research outputs found

    Page-Differential Logging: An Efficient and DBMS-independent Approach for Storing Data into Flash Memory

    Full text link
    Flash memory is widely used as the secondary storage in lightweight computing devices due to its outstanding advantages over magnetic disks. Flash memory has many access characteristics different from those of magnetic disks, and how to take advantage of them is becoming an important research issue. There are two existing approaches to storing data into flash memory: page-based and log-based. The former has good performance for read operations, but poor performance for write operations. In contrast, the latter has good performance for write operations when updates are light, but poor performance for read operations. In this paper, we propose a new method of storing data, called page-differential logging, for flash-based storage systems that solves the drawbacks of the two methods. The primary characteristics of our method are: (1) writing only the difference (which we define as the page-differential) between the original page in flash memory and the up-to-date page in memory; (2) computing and writing the page-differential only once at the time the page needs to be reflected into flash memory. The former contrasts with existing page-based methods that write the whole page including both changed and unchanged parts of data or from log-based ones that keep track of the history of all the changes in a page. Our method allows existing disk-based DBMSs to be reused as flash-based DBMSs just by modifying the flash memory driver, i.e., it is DBMS-independent. Experimental results show that the proposed method improves the I/O performance by 1.2 ~ 6.1 times over existing methods for the TPC-C data of approximately 1 Gbytes.Comment: 37 page

    SSDFS: Towards LFS Flash-Friendly File System without GC operation

    Full text link
    Solid state drives have a number of interesting characteristics. However, there are numerous file system and storage design issues for SSDs that impact the performance and device endurance. Many flash-oriented and flash-friendly file systems introduce significant write amplification issue and GC overhead that results in shorter SSD lifetime and necessity to use the NAND flash overprovisioning. SSDFS file system introduces several authentic concepts and mechanisms: logical segment, logical extent, segment's PEBs pool, Main/Diff/Journal areas in the PEB's log, Diff-On-Write approach, PEBs migration scheme, hot/warm data self-migration, segment bitmap, hybrid b-tree, shared dictionary b-tree, shared extents b-tree. Combination of all suggested concepts are able: (1) manage write amplification in smart way, (2) decrease GC overhead, (3) prolong SSD lifetime, and (4) provide predictable file system's performance
    corecore