A data synchronization method, system and apparatus are provided. The method includes receiving a request including data to be uploaded, from a client, and responding to the request after data is successfully obtained from the client, and storing the obtained data. For data whose size is less than a threshold value, a synchronization request is sent to a standby server to request the standby server to store the data. Otherwise a second type work log, including information indicating that data that has not been synchronized, is generated and stored. Data whose size is greater than or equal to the threshold value is not synchronized immediately, but is recorded in the work log. In some cases, data whose size is less than the threshold value, but fails to be synchronized, is recorded in the work log. Synchronization of this data may be subsequently completed according to the work log, so that the synchronization of this data can avoid affecting synchronization of other data. A first-type work log comprising information about the data may be generated and stored in response to the data being synchronized to the standby server successfully. Data that has not been synchronized to the standby server, according to the indication information, may be locally read and the data sent to the standby server to be stored. Data may be sent to the standby server to replace other data, in response to verification codes, such as hash codes, being inconsistent. The first and second work logs may also be sent to a log backup device. Responding to the uploading request and sending data to the standby server may occur asynchronously.