基于闪存的剖分影像数据专用存储技术研究

发布时间：2018-02-20 18:58

本文关键词： 剖分影像数据固态存储 Hilbert编码窗口查询　出处：《国防科学技术大学》2012年硕士论文　论文类型：学位论文

【摘要】：剖分影像数据存储一直是遥感影像信息系统中的关键问题。机械磁盘的性能提升已经达到一定的瓶颈，它正制约着遥感影像信息系统的发展。由于容量大、速度快、低功耗、抗震性强，以闪存为主要介质的固态硬盘正逐步取代机械硬盘成为存储领域的后起之秀。研究基于闪存的剖分影像数据专用存储技术，是一个很有价值的课题。 LazyFTL是一种基于多通道并行存储架构的地址映射方式，然而将它应用到剖分影像数据存储时，忽视了通道间的并行化操作，存储和访问速率受到限制。本文分析了剖分影像数据量大、随机访问时效性高的特点，明确了剖分影像数据快速存储的性能要求，提出了一种基于Hilbert曲线的剖分影像分块地址映射方法。在算法中，采用查找表的方法提高了任意尺寸图像块Hilbert编码的计算效率，加快了图像数据地址映射表的生成速率；采用图像数据与元数据分开存储的方式，将索引信息节点存储到单独的Flash物理页中，减少了存储设备启动时需要扫描的Flash物理页数量，缩短了固态硬盘启动时间。另外，本文根据剖分影像数据访问的特点，提出了一种基于窗口查询的缓存置换算法。在该算法中，改变了一般固态硬盘中基于LRU访问频率统计的置换区判断方法，，采用一种基于空间相关性的置换区判断方法，提高了数据访问命中率和数据读取速度。实验结果表明，基于Hilbert曲线的剖分影像分块地址映射方法可以获得1.6GB/s的存储速率，优于LazyFTL的映射方式；基于窗口查询的缓存置换算法可以获得32.7%的缓存命中率，明显优于基于LRU的缓存置换算法，大大地提高数据访问速率。
[Abstract]:The storage of partitioned image data has always been a key problem in remote sensing image information system. The performance improvement of mechanical disk has reached a certain bottleneck, which is restricting the development of remote sensing image information system. The solid state hard disk with flash memory as the main medium is gradually replacing the mechanical hard disk as a rising star in the field of storage. It is a valuable subject to study the special storage technology of split image data based on flash memory. LazyFTL is an address mapping method based on multi-channel parallel storage architecture. However, when it is applied to the storage of split image data, the parallelization operation between channels is ignored. The storage and access rate are limited. This paper analyzes the characteristics of large amount of data and high time efficiency of random access of partitioned images, and clarifies the performance requirements of fast storage of partitioned image data. In this paper, a method of segmented image block address mapping based on Hilbert curve is proposed. In the algorithm, the method of lookup table is used to improve the computational efficiency of Hilbert coding for arbitrary size image blocks, and to speed up the generation rate of image data address mapping table. The index information node is stored in a separate Flash physical page by using the method of separate storage of image data and metadata, which reduces the number of Flash physical pages that need to be scanned when the storage device starts, and shortens the startup time of solid state hard disk. In this paper, according to the characteristics of data access in subdivision image, a cache permutation algorithm based on window query is proposed. In this algorithm, the permutation region judgment method based on LRU access frequency statistics in general solid-state hard disk is changed. A new method based on spatial correlation is used to judge the permutation area, which improves the hit rate of data access and the speed of data reading. The experimental results show that the block address mapping method based on Hilbert curve can obtain the storage rate of 1.6 GB / s, which is superior to that of LazyFTL, and the cache replacement algorithm based on window query can obtain a cache hit ratio of 32.7%. It is obviously superior to the cache replacement algorithm based on LRU, and greatly improves the data access rate.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP333

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