Data check method and storage system

A storage system includes a host, a check node, and multiple data nodes. The host is configured to: divide multiple data write requests into multiple data write request sets according to data node identifiers included in the data write requests, where each data write 5 request set includes multiple data write requests having a same data node identifier; and when sizes of all data write requests in each of a specified quantity of data write request sets reach a preset data amount, calculate check data of the specified quantity of data write request sets. The host is further configured to: send each data write request set to a data node indicated by an identifier, and send the check data to the check node. Therefore, on a basis of ensuring 10 data reliability, data of a same type can be stored in a same storage node and the data can be read from only one storage node, thereby improving data reading efficiency.