Design And Implementation Of Hybrid Storage Systems For Key-Value Database

With the rapid development of large-scale Internet applications, high scalabilityrequirements is so important to the storage system that key-value database due to itssimple and efficient data model to traditional database systems have stage in the art. Onthe other hand, with the hardware development, gradually increase the cost-effectivesolid-state disk, the system has become more and more preferred, the random read of theadvantages and features of Internet applications, a high degree of fit, but its relatively lowwrite and erase performance limit the number of its impact scenarios, so the combinationof solid-state disk and the disk storage system has been the integration of everyone’sattention, this article focus on hybrid system of solid-state disk and magnetic disk forkey-value database.To our own web applications, the way we order the log records in the database forkey-value operations, all operations are just a sequence of write memory, when the data inmemory after reaching a certain threshold, after a brush to write midrange, the log is onthe way to a certain extent at the expense of read performance to optimize writeperformance, so there is a natural and complementary relationship between the SSD. weuse a hierarchical method to write the different file into different place with specificplacement and migration strategy. Using database file access pattern, We store log file inMagnetic disk because it’s once-written and rarely read. We store metadata file in SSDbecause it’s frequently read and written but really small. We choose Probabilistic way tostore SSTable file in write-only workload, achieving5%-56%performance improvementto Flashcache, We use LRU way to store SSTable file in mixed workload, achieving4%-14%performance improvement to Flashcache.