Potentiality of power management on database systems with power saving function of disk drives

Power consumption of modern datacenters is increasing rapidly. Databases, especially OLTPs, have become a major application at datacenters. Therefore, power-saving management for OLTP applications has become an important task for user budgets and datacenter operations. A recent report described that disk drives consume about 70% of total power of IT equipment when such large OLTP applications are executed. As described in this paper, we specifically examine a novel power-saving management for multiple disk drives of OLTP applications. First, we constructed an experimental system with power meter, and measured basic power consumption and I/O behaviors of OLTP applications. Then we show that basic measurement results confirm there is still the potentiality of power-saving even though OLTP applications are running. We propose a new method that delays database writes based on this I/O behavior knowledge at run time. Experimental and simulation results obtained using our power-saving methods are explained. Our method provides dynamic power saving of disk drives running TPC--C applications, which issue many I/Os to the disk drives.