Management method of mapping table caches in solid-state disk system

Abstract

The invention discloses a management method of mapping table caches in a solid-state disk system. For a solid-state disk with page mapping tables stored on a flash memory, a two-stage chain type organizational structure is adopted in the method, and mapping entries belonging to the same mapping page in the caches are organized together. When dirty entries in the caches need to be replaced, replaced dirty entries and other dirty entries belonging to the same mapping page with the replaced dirty entries are updated and returned to the page mapping tables of the flash memory through a batch updating method, and therefore extra overhead caused by cache replacement is greatly reduced; when the caches are not hit, a dynamic pre-fetching technology is used, the pre-fetching length is determined according to loading overhead, replacement cost and the continuous precursor number of historical access, the hit rate of the caches is increased, and extra overhead caused by cache loading is reduced. The performance of the solid-state disk is improved through batch updating and the dynamic pre-fetching technology, and the service life of the solid-state disk is prolonged.

Description

technical field [0001] The invention belongs to the technical field of solid-state disk storage, and more specifically relates to a mapping table cache management method in a solid-state disk system. Background technique [0002] A flash-based solid state disk (Solid State Disk, SSD) has the advantages of high performance, anti-vibration, low power consumption, and the like. As people's demand for storage continues to increase, SSDs have gradually become an important part of computer storage systems. It has become an effective supplement to disk in many storage systems. At present, SSD has been widely used in various industries such as banking, finance, aviation, military, and communication, and has formed a global market worth tens of billions per year. [0003] At present, solid-state disks generally use NAND flash memory as the storage medium. The hierarchical structure of flash memory chips is shown in the attached figure 1 As shown, each chip is composed of multiple ...

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Problems solved by technology

(3) The erasing times of the flash memory block are limited, that is, the service life of the flash memory is limited

[0007] The existing mapping table caching algorithm has the following obvious deficiencies: 1. The mapping table caching algorithm of DFTL and S-FTL fails to combine the read and write characteristics of solid state disk well when organizing the mapping entries in the mapping cache. 2. DFTL's mapping table caching algorithm does not fully exploit the spatial locality of the load, resulting in a low cache hit rate; 3. Each mapping page on the flash memory contains hundreds or thousands of mappings Entries, S-FTL's mapping table caching algorithm uses mapping pages as the caching unit, which will cause less accessed entries in the page to also reside in the cache, reducing the space utilization of the cache

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