Research On Database Characteristics Oriented SSD Write Cache

Database system is an important way for enterprises to store and manage data,and has been widely used in the industry.Companies have disk-based storage systems,due to their business development requirements,they need provide services for new applications.The characteristics of new applications are different,the storage system may be different,but the performance and characteristics of the storage system often fail to meet the new application requirements.When taking into account cost considerations,SSD cache can solve the above problems.Applying a database on a disk-based storage system,the SSD cache can avoid the impact of poor random read and write performance of traditional disks.For the SSD cache of the database system,a general cache solution needs to be designed for different databases,and different database workloads have similar I/O characteristics,the SSD cache needs to recognize these features to adjust its caching strategy dynamically.The I/O of the database can be divided into two types: I/O of the data file and I/O of the log file.Through the analysis of the database I/O,there are a large number of random write I/O in the database system,mainly caused by log file.This I/O characteristic is very salient,the corresponding I/O area is mainly written.These random write I/O are the main reasons that restrict the performance of the database applications,so the write I/O optimization of the database can significantly improve the performance of the database.Based on the above analysis,the SSD-based database write optimization scheme WOC(Write-only Cache)is proposed: the I/O features are extracted periodically by collecting database I/O data,the statistics prediction algorithm can predict future database I/O characteristics,and put the predicted data into the SSD for caching,thereby improving the performance of the database.The test results show: WOC scheme can significantly improve the performance of the database,and only very small amount of SSD is used.The comprehensive index evaluation shows that WOC is the best choice compared to other schemes in terms of performance and cost balance.