Solid state disk intelligent garbage recycling and scheduling method

Abstract

The invention provides a solid state disk intelligent garbage recycling and scheduling method. According to the method, the type of generated GC is determined through two levels of thresholds. Read-write erasing operation capable of interrupting garbage collection is combined with read-write IO of each channel for management, and available space is actively recycled by fully utilizing idle time ofeach channel. An interruptible garbage collection IO queue is set, a GC buffer area is used for temporarily storing and recycling effective pages of damaged blocks, the writing operation of the interruptible garbage collection effective pages is delayed, and the influence of GC on host IO is reduced. For non-interruptible GC, a greedy strategy is adopted for selection of damaged blocks, the blockwith the most invalid pages is selected, and GC efficiency is maximized. For interruptible GC, the recovery efficiency, the data updating frequency and the erasure frequency are comprehensively considered for selection of damaged blocks, and the garbage recovery efficiency and abrasion balance are considered. According to the method, the GC efficiency can be ensured, Meanwhile, the influence of GC on host IO is reduced.

Description

technical field [0001] The invention belongs to the field of solid-state hard disk (SSD) firmware algorithm design, and particularly relates to a solid-state hard disk intelligent garbage collection (GC) and scheduling method. Background technique [0002] With the development of semiconductor technology, in computer systems, the storage subsystem has become a bottleneck restricting the development of computer systems. Due to its high-speed read and write performance, SSD based on NAND flash memory has become one of the mainstream storage devices. [0003] NAND flash memory, the storage medium of SSD, has the following physical characteristics: 1) Flash memory only provides three operations: read, write, and erase, and the performance of these three operations is asymmetrical. Read is the fastest, followed by write, and erase is the slowest; 2) Flash memory is organized in the structure of pages, blocks and planes; a page is the smallest unit of read / write, generally 2 / 4 / 8K...

AI Technical Summary

Problems solved by technology

[0003] NAND flash memory, the storage medium of SSD, has the following physical characteristics: 1) Flash memory only provides three operations: read, write, and erase, and the performance of these three operations is asymmetrical, with the fastest read, followed by write, and the slowest erase; 2) Flash memory is organized according to the structure of pages, blocks, and planes; a page is the smallest unit of reading / writing, generally 2 / 4 / 8KB; a block is the smallest unit of erasing, and a block generally contains 64 / 128 pages; 3) After the flash memory is erased, it can only be written once, that is, the so-called erase-before-write, which causes the flash memory to not support in-place update; 4) The number of programming / erasing (P / E) of each storage unit of the flash memory is limited. After / E times, flash storage data is no longer reliable

[0004] Due to the above physical characteristics of NAND flash memory, SSD can only adopt an off-site update strategy: invalidate the previously written data, and then write the data to a new location

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