Hybrid Storage Management for Database Systems

The use of flash-based solid state drives (SSDs) in storage systems is growing. Adding SSDs to a storage system not only raises the question of how to manage the SSDs, but also raises the question of whether current buffer pool algo-rithms will still work effectively. We are interested in the use of hybrid storage systems, consisting of SSDs and hard disk drives (HDDs), for database management. We present cost-aware replacement algorithms, which are aware of the difference in performance between SSDs and HDDs, for both the DBMS buffer pool and the SSDs. In hybrid storage sys-tems, the physical access pattern to the SSDs depends on the management of the DBMS buffer pool. We studied the im-pact of buffer pool caching policies on SSD access patterns. Based on these studies, we designed a cost-adjusted caching policy to effectively manage the SSD. We implemented these algorithms in MySQL’s InnoDB storage engine and used the TPC-C workload to demonstrate that these cost-aware al-gorithms outperform previous algorithms. 1