A computer-implemented method comprising: maintaining, by a storage system, multiple tiers of storage devices, the multiple tiers of storage devices being layered in a hierarchical structure based on one or more performance characteristics, the multiple tiers of storage devices comprising at least a first tier storage device and a second tier storage device, wherein the first tier storage device has a first performance characteristic of the one or more performance characteristics that is superior to the first performance characteristic of the second tier storage device, the first performance characteristic comprises one or more of an access speed, an access bandwidth, or an access latency, and the first tier storage device is configured to store blockchain data that is more frequently accessed than blockchain data stored in the second tier storage device; receiving a write request of ledger data, wherein the ledger data comprises one of blockchain transaction data, blockchain block data, blockchain index data, or blockchain state data generated by a blockchain network; determining whether a type of the ledger data is blockchain block data, wherein the blockchain block data comprises at least one block in a blockchain, and the at least one block comprises one or more blockchain transactions and a hash value of a previous block in the blockchain; in response to determining that the type of the ledger data is blockchain block data, writing the ledger data into the second tier storage device, wherein the second tier storage device has a larger storage space than the first tier storage device; in response to determining that the type of the ledger data is not blockchain block data, determining a usage level of the first tier storage device; determining whether the usage level of the first tier storage device is below a predetermined threshold; in response to determining that the usage level of the first tier storage device is below the predetermined threshold, writing the ledger data into the first tier storage device; and in response to determining that the usage level of the first tier storage device reaches or exceeds the predetermined threshold, writing the ledger data into the second tier storage device. maintaining, by a storage system, multiple tiers of storage devices, the multiple tiers of storage devices being layered in a hierarchical structure based on one or more performance characteristics, the multiple tiers of storage devices comprising at least a first tier storage device and a second tier storage device, wherein the first tier storage device has a first performance characteristic of the one or more performance characteristics that is superior to the first performance characteristic of the second tier storage device, the first performance characteristic comprises one or more of an access speed, an access bandwidth, or an access latency, and the first tier storage device is configured to store blockchain data that is more frequently accessed than blockchain data stored in the second tier storage device; receiving a write request of ledger data, wherein the ledger data comprises one of blockchain transaction data, blockchain block data, blockchain index data, or blockchain state data generated by a blockchain network; determining whether a type of the ledger data is blockchain block data, wherein the blockchain block data comprises at least one block in a blockchain, and the at least one block comprises one or more blockchain transactions and a hash value of a previous block in the blockchain; in response to determining that the type of the ledger data is blockchain block data, writing the ledger data into the second tier storage device, wherein the second tier storage device has a larger storage space than the first tier storage device; in response to determining that the type of the ledger data is not blockchain block data, determining a usage level of the first tier storage device; determining whether the usage level of the first tier storage device is below a predetermined threshold; in response to determining that the usage level of the first tier storage device is below the predetermined threshold, writing the ledger data into the first tier storage device; and in response to determining that the usage level of the first tier storage device reaches or exceeds the predetermined threshold, writing the ledger data into the second tier storage device.