In a method, identifiers are obtained of N to-be-upgraded nodes. An upgrade sequence of the N to-be-upgraded nodes is set according to the identifiers of the N to-be-upgraded nodes. A backup node of each to-be-upgraded node is determined according to the upgrade sequence of the N to-be-upgraded nodes, to obtain node backup information. A backup node of the Xth to-be-upgraded node is at least one node in a set that includes a to-be-upgraded node prior to the Xth to-be-upgraded node and a to-be-upgraded node following the (X+[Z+1])th to-be-upgraded node. Z is a ratio of a time required by the Xth to-be-upgraded node for migrating back service data to an online upgrade time of the Xth to-be-upgraded node. The node backup information is sent to the N to-be-upgraded nodes.