Write cache method, cache synchronization method and device

Abstract

The invention provides a write cache method, cache synchronization method and device, wherein the write cache method comprises the following steps: if a cache device is cached with old data at a disc address same as that of data to be cached, a version number of the data to be cached is updated such that the version number of the data to be cached indicates that the data to be cached is written in the cache device later than the old data, and the cache address of the old data is used as the cache address of a previous version of the data to be cached, wherein the old data is old data having the same disc address with the data to be cached; the version number of each data to be cached, the disc address, the cache address of the previous version and the data to be cached are written into a memory block; after a memory block page is written with data, the data in the memory block is written into a cache block on the cache device; and the version number of data to be cached, the disc address and the cache address of the previous version are the page descriptors of the page where the data to be cached is stored. According to the invention, cache blocks on the write cache device are in concurrency.

Description

technical field [0001] Embodiments of the present invention relate to computer technology, and in particular to a write cache method, cache synchronization method and device. Background technique [0002] The current new storage devices have the advantage of fast access speed, and even have non-volatile characteristics-that is, the characteristics that data will not be lost after power failure. Take flash-based SSD as an example, its price and access speed are between memory and ordinary disk, and it has non-volatile characteristics, which is suitable for caching between memory and disk. When using this type of storage device as a cache device between the memory and disk of the database system, the same data block in the memory may be modified multiple times. After the sequential write cache operation, the same data will exist on the cache device Multiple copies (versions) of a block. How to effectively manage these multi-version data blocks and efficiently utilize the cac...

AI Technical Summary

Problems solved by technology

[0005] Embodiments of the present invention provide a write cache method, cache synchronization method and device, which are used to solve the defects of low write cache efficiency and the defect that data in the cache device cannot be written to the disk in time in the prior art, and improve the space utilization of the cache device Rate

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