A storage system includes a host, a check node, and multiple data nodes. The host groups multiple data write requests into multiple data write request sets according to data node identifiers included in the data write requests. Each data write request set includes multiple data write requests having a same data node identifier. When a size of all data write requests in each of a specified quantity of data write request sets reaches a preset data amount, the host calculates check data of the specified quantity of data write request sets. Further, the host sends each data write request set to a data node indicated by an identifier, and sends the check data to the check node. Therefore, 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.