NandFlash address mapping and block management algorithm

Abstract

The invention provides a NandFlash address mapping and a block management algorithm. The NandFlash address mapping and the block management algorithm are a part of the firmware design of a solid-statedisc controller, and mainly play the following roles: 1, the address information taking a sector as a unit sent by a mainframe is translated into a physical block and a page address of a NandFlash chip; 2, each block of the NandFlash chip is used as evenly as possible through the block management algorithm, the usage rate of each block is improved, the unnecessary erasure operations are avoided,the number of times of the block erased is reduced, which is commonly known as load balancing; 3, the bad blocks are managed in the using process to ensure the reliability of data; 4, optimized NandFlash multi-channel address mapping design is adopted to realize multi-channel parallel / pipeline operations.

Description

technical field [0001] The invention relates to the field of storage technology, in particular to a NandFlash address mapping and block management method. Background technique [0002] NAND Flash can greatly reduce the cost per bit of flash memory by reducing the process size and adopting multi-level technology, but this also brings other problems, mainly manifested in the degradation of device performance: such as decreased access speed, increased bit error rate, durability degree of degradation and deterioration of retention characteristics, etc. Among them, endurance refers to the maximum programming and erasing times (P / E Cycles) that a memory cell can withstand. The reason why there is a maximum number of times of erasing and writing is that the programming and erasing operations of flash memory are carried out through the electron tunneling mechanism, and a large number of tunneling will cause stress on the tunneling oxide layer, resulting in the electrical performanc...

AI Technical Summary

Problems solved by technology

[0015] The present invention provides a kind of NandFlash address mapping and block management method, has solved the problem of using NandFlash efficiently, because the characteristic of NandFlash chip, as storage organization structure with page, block (currently NandFlash chip generally every page is 2K or 4K byte , each block has 64 pages), the erasing operation must be performed before rewriting the data, the erasing is in the unit of "block", and the number of erasing is limited, bad blocks will appear during use, etc.; while the operating system accesses the disk It is carried out with the sector (512 bytes) as the smallest unit, which requires mapping conversion between the logical sector number issued by the operating system and the physical address of the NandFlash chip; in addition, system data such as the partition table and the user's common Data needs to be rewritten frequently, which will cause some blocks of the Flash chip to be erased frequently, and the life span will be reduced; frequent erasing will also reduce the read and write speed of the disk; at the same time, the generation of bad blocks will affect the reliability of data. bring hidden danger

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