Method for building reliable flash memory storage systems using erasure and error correction codes in concert

Abstract

The invention discloses a construction method of a reliable flash memory storage system using erasure correction codes and error correction codes. The steps include: receiving an IO request R, determining the type of read and write; Pages use erasure codes to generate a total of s+k pages to be written, and write them to the storage device together with the checksum and error correction codes of each page; divide the read request into sub-requests belonging to different stripes, and for each Sub-request, read each page and its checksum and error correction code, calculate the checksum of each page and identify bit errors, find out the page with the most bit errors, if the number of bit errors on this page is not greater than the correcting code used The maximum number of error bits T that can be corrected by the error code, use the error correction code to correct the bit error in the sub-request, otherwise use the erasure code to correct the bit error in the sub-request, and return the data of the sub-request. The invention has the advantages of low calculation overhead, fast IO speed and remarkable effect of prolonging the service life of the flash memory.

Description

technical field [0001] The invention relates to the field of computer storage systems, in particular to a construction method of a reliable flash memory storage system using erasure correction codes and error correction codes in cooperation. Background technique [0002] Flash memory is widely deployed in large-scale storage systems because of its superior performance. However, its limited lifespan hinders the promotion of flash memory under write-intensive loads to some extent. The lifespan of flash memory refers to the number of erasing and writing that each storage unit can withstand. When a manufacturer launches a flash memory chip, it will give the corresponding nominal life of the chip. If the number of times of erasing and writing of each storage unit is within the nominal life, the bit error rate of the flash memory is low, and the data stored on the flash memory is considered to be reliable. In fact, the flash memory can still save data in a large range after the ...

AI Technical Summary

Problems solved by technology

[0005] A comprehensive comparison of the above two error-tolerant mechanisms shows that error-correcting codes are only suitable for scenarios with low error rates. Erasure coding is suitable for scenarios with high error rates. It can correct a large number of bit errors in data with strong error tolerance, and the computational overhead is constant. However, when there are few bit errors, the computational overhead of erasure coding is higher than that of error correction. code

Using the above two mechanisms independently is difficult to extend the life of flash memory beyond the manufacturer's nominal life while ensuring IO performance

Images