This application discloses a data writing method. A network controller performs erasure code encoding on original data, and writes a third quantity of target data blocks of a plurality of obtained target data blocks into a storage node. The network controller reads a first quantity of target data blocks of the third quantity of the target data blocks from the storage node, and decodes the read target data blocks. The plurality of target data blocks include a first quantity of original data blocks and a second quantity of check data blocks, two ends of a target data block include same version information, and the third quantity is greater than the first quantity.