Flash memory system and managing and collecting methods for flash memory with invalid page messages thereof

Abstract

A flash memory system and managing and collecting methods for flash memory with invalid page messages thereof are described. When the valid data pages of the flash memory are changed to invalid data pages, a recording area is used to record the message of the invalid data pages to effectively collect the occupied space of the invalid data pages in the flash memory. Further, while garbage collecting step is performed, a block is rapidly selected according to the message of the recording area and the valid data pages in the selected block are correctly identified, copied and removed.

Description

technical field [0001] The present invention relates to a memory system and a method for managing and recovering invalid data page information of the memory, in particular to a flash memory system and a method for managing and recovering invalid data page information of the flash memory. Background technique [0002] A flash memory is composed of multiple pages, and 64 pages or 128 pages are defined as a block, which is used as a storage unit of the flash memory. However, the characteristic of flash memory is that after a page is written into data, new data cannot be rewritten to the page immediately, and the block (block) where the page is located must be erased (erase) before continuing. The page is written with new data. However, the above method of erasing the block and then rewriting the data is quite time-consuming, so usually the update data to be written to the page is first written to another physical address corresponding to the same logical address. [0003] For...

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Problems solved by technology

However, the above method is only applicable to single-level cell (single-level cell, SLC) flash memory, not applicable to multi-level cell (multi-level cell, MLC) flash memory, because multi-level cell (MLC) can only One-time writing, but cannot be carried out by writing flags to the spare area (spare area) in a single-level storage unit (SLC), and cannot be used as a basis for judging whether the page is valid

In another prior art, if all pages of all blocks are recorded as "invalid" (invalid) or "valid" (valid), as a basis for judging whether the pages are valid, it will It consumes a considerable amount of additional memory space to store these recorded states

[0005] In addition, in the application of flash memory, the corresponding relationship between logical addresses and physical addresses is limited, that is, the data of the same logical block is placed in the same physical block. Data (cold data) may be placed in the same logical block, so when it is desired to determine whether there is a valid data page in the physical block, it is necessary to scan the physical block corresponding to the entire logical block, resulting in memory recovery (GC ) is significantly less effective

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