A method, device and system disclosed used in storage technique, comprising: splitting a file of size M into k blocks, that is to say, each block is of size M/k; issuing the above k blocks across k different storage nodes in the distributed network storage system in a distributed manner; using the k blocks, constructing n−k independent blocks via linear coding method, and satisfying the property that any k of the n encoded blocks can be used to reconstruct the original data in the file, which means the linear coding method is a kind of Maximum-Distance Separable (MDS) code; distribute the n−k encoded blocks to the rest n−k different storage codes in the distributed network storage systems.