LOG-STRUCTURED STORAGE SYSTEMS

Disclosed herein are methods, systems, and apparatus, including computer programs encoded on computer storage devices, for data processing and storage. One of the method includes: maintaining a plurality of tiers of storage devices and one or more tiers of caches by a storage system for storing blockchain data, the plurality of tiers of storage devices including at least a higher-tier storage device and a lower-tier storage device; determining that a blockchain data object in a data log file stored in a lower-tier storage device is an active data object, wherein the blockchain data object is block data, transaction data, or state data; and writing the data object into a cache of the one or more tiers of caches.