Storage system and method for predictive rebalancing and controller node management based on load prediction

A storage system control method executed by a storage system including a plurality of drive nodes, a plurality of controller nodes controlling data from a host device to the plurality of drive nodes, and a processor, the method comprising:

• by the processor;
• calculating long-term load fluctuation prediction as prediction of load fluctuation over a certain period of time in future of the plurality of controller nodes based on time-series data of load of the plurality of controller nodes;
• calculating an addition/reduction completion target time to complete addition or reduction of an operating controller node out of the plurality of controller nodes based on the long-term load fluctuation prediction and a load threshold value determined from a power performance model representing a relationship between the load and energy efficiency of the plurality of controller nodes;
• calculating a rebalancing time for a rebalancing process based on a predicted amount of data movement for the rebalancing process for moving data between the plurality of drive nodes in accordance with the addition or the reduction, constraint conditions, and bandwidth information of a path for the data movement;
• calculating a start time of the rebalancing process from the addition/reduction completion target time and the rebalancing time;
• and
• starting the rebalancing process at the start time.