Self-tuning Page Cleaning in DB2

Storage management is an important part of DB2. The buffer pool in DB2 is used to catch the disk pages of the database, and its management algorithm can significantly affect performance. Because of the complexity of DB2 and the workloads running on it, the buffer pool management algorithm is hard to study, config, and tune. In order to investigate the buffer pool management algorithm under controlled circumstances, a trace of buffer pool requests was collected and a trace-driven simulator was developed. The impact of various parameters of the buffer pool management algorithm was studied in the simulator. Relationships among different activities competing for storage space and the I/O channel were examined. A selftuning algorithm for buffer pool management was developed and tested in both the simulator and DB2. Simulation tests showed that the new algorithm can achieve comparable performance to a hand-tuned system. The experiments in DB2 on a small and a medium TPC-C database verified the simulation results.