Provided are a database rebalancing method including three or more database (DB) nodes, the method comprises configuring a first node set including two or more DB nodes from among the three or more DB nodes included in the storage system, performing a first partial rebalancing between DB nodes of the first node set, during the first partial rebalancing, performing a first partial rebalancing cover step in which DB nodes excluded from the first node set perform a normal operation, configuring a second node set including two or more DB nodes from among the three or more DB nodes included in the storage system, performing a second partial rebalancing between DB nodes of the second node set, the second partial rebalancing being performed after completion of the first partial rebalancing and during execution of the second partial rebalancing, performing a second partial rebalancing cover step in DB nodes excluded from the second node set perform a normal operation, wherein at least one DB node included in the first node set is not included in the second node set, or at least one DB node included in the second node set is not included in the first node set.