Data caching and reading method and data access system

The invention relates to a data caching and reading method and a data access system. A client sends a first request to the data storage system to obtain the metadata of the target data. The client sends a second request to the data caching system, wherein the second request comprises the metadata. A data caching system judges whether cached target data consistent with the target data stored in the data storage system is cached or not based on the metadata. The client obtains the target data from the data caching system under the condition that the consistent cached target data is judged to be cached. When it is judged that the consistent cached target data is not cached, the client obtains the target data from the data storage system and sends the obtained target data to the data caching system so as to cache the target data. Therefore, whether the data cached by the data caching system is consistent with the corresponding data stored in the data storage system can be conveniently, quickly and accurately judg