A consensus method performed in a cluster system that includes a plurality of nodes, wherein the plurality of nodes jointly run a plurality of instances, each of the plurality of instances is jointly run by the plurality of nodes, and there is one primary instance and one or more secondary instances in the plurality of instances, wherein for each instance, one of the plurality of nodes serves as a primary node corresponding to the instance and a plurality of primary nodes corresponding to the plurality of instances are different nodes, wherein the method comprises: sending, by a first node, a service request to M backup nodes, wherein the first node is a primary node corresponding to an instance in the plurality of instances, the M backup nodes are backup nodes in the plurality of nodes, running the instance, M is a positive integer, and the service request comprises packaging a transaction, generating a block of transaction information, or requesting transaction information; receiving, by the first node, first authentication information returned by N backup nodes, wherein the first authentication information comprises a signature of a backup node generating the first authentication information, the first authentication information indicates that the backup node generating the first authentication information authenticates the service request successfully, and N is a positive integer less than or equal to M; if a quantity N of pieces of first authentication information received by the first node exceeds a second preset threshold, performing, by the first node, the service request; and sending, by the first node, first acknowledgement information to the M backup nodes, wherein the first acknowledgement information comprises signatures that are of the N backup nodes and that are comprised in the first authentication information returned by the N backup nodes, and the first acknowledgement information is used to enable the M backup nodes to perform the service request. sending, by a first node, a service request to M backup nodes, wherein the first node is a primary node corresponding to an instance in the plurality of instances, the M backup nodes are backup nodes in the plurality of nodes, running the instance, M is a positive integer, and the service request comprises packaging a transaction, generating a block of transaction information, or requesting transaction information; receiving, by the first node, first authentication information returned by N backup nodes, wherein the first authentication information comprises a signature of a backup node generating the first authentication information, the first authentication information indicates that the backup node generating the first authentication information authenticates the service request successfully, and N is a positive integer less than or equal to M; if a quantity N of pieces of first authentication information received by the first node exceeds a second preset threshold, performing, by the first node, the service request; and sending, by the first node, first acknowledgement information to the M backup nodes, wherein the first acknowledgement information comprises signatures that are of the N backup nodes and that are comprised in the first authentication information returned by the N backup nodes, and the first acknowledgement information is used to enable the M backup nodes to perform the service request.