Disclosed herein are methods, systems, and apparatus, including computer programs encoded on computer storage media, for data storage. One of the methods includes: receiving data for storage from a service platform, wherein the data includes mutable data, immutable data, and index data identified by the service platform; storing the mutable data in a cache storage, wherein the mutable data is to be executed by a smart contract; initiating, a consensus algorithm to record the immutable data on a blockchain; in response to successfully performing the consensus algorithm, recording, based on invoking the smart contract, the immutable data on the blockchain, wherein the blockchain is stored in a database that has lower storage cost than the cache storage; and linking, based on invoking the smart contract, the mutable data and the immutable data based on the index data.