A method for synchronizing a logical block address to physical page number mapping table, comprising: obtaining, by a primary device, a first entry index from a storage device, wherein the first entry index is an index corresponding to an updated entry in a first logical block address to physical page number mapping table locally stored in the storage device; selectively determining, by the primary device, a second entry index from the first entry index, wherein the second entry index is a part of indexes in the first entry index, and sending a first command to the storage device to request the storage device to send a first entry corresponding to the second entry index; receiving, by the primary device, the first entry fed back by the storage device in response to the first command; and updating, by the primary device based on the first entry, a second logical block address to physical page number mapping table locally stored in the primary device; wherein the obtaining, by the primary device, the first entry index comprises: sending, by the primary device, a second command to the storage device, wherein the second command indicates the storage device to feed back the first entry index; and receiving, by the primary device, the first entry index fed back by the storage device in response to the second command; wherein the selectively determining, by the primary device, the second entry index from the first entry index comprises: determining, by the primary device, the second entry index based on importance of data in an entry corresponding to each index in the first entry index; wherein the determining, by the primary device, the second entry index based on importance of data in an entry corresponding to each index in the first entry index comprises: determining, by the primary device, the second entry index based on a quantity of access times of the data in the entry corresponding to each index in the first entry index. obtaining, by a primary device, a first entry index from a storage device, wherein the first entry index is an index corresponding to an updated entry in a first logical block address to physical page number mapping table locally stored in the storage device; selectively determining, by the primary device, a second entry index from the first entry index, wherein the second entry index is a part of indexes in the first entry index, and sending a first command to the storage device to request the storage device to send a first entry corresponding to the second entry index; receiving, by the primary device, the first entry fed back by the storage device in response to the first command; and updating, by the primary device based on the first entry, a second logical block address to physical page number mapping table locally stored in the primary device; wherein the obtaining, by the primary device, the first entry index comprises: sending, by the primary device, a second command to the storage device, wherein the second command indicates the storage device to feed back the first entry index; and receiving, by the primary device, the first entry index fed back by the storage device in response to the second command; wherein the selectively determining, by the primary device, the second entry index from the first entry index comprises: determining, by the primary device, the second entry index based on importance of data in an entry corresponding to each index in the first entry index; wherein the determining, by the primary device, the second entry index based on importance of data in an entry corresponding to each index in the first entry index comprises: determining, by the primary device, the second entry index based on a quantity of access times of the data in the entry corresponding to each index in the first entry index. sending, by the primary device, a second command to the storage device, wherein the second command indicates the storage device to feed back the first entry index; and receiving, by the primary device, the first entry index fed back by the storage device in response to the second command; wherein the selectively determining, by the primary device, the second entry index from the first entry index comprises: determining, by the primary device, the second entry index based on importance of data in an entry corresponding to each index in the first entry index; wherein the determining, by the primary device, the second entry index based on importance of data in an entry corresponding to each index in the first entry index comprises: determining, by the primary device, the second entry index based on a quantity of access times of the data in the entry corresponding to each index in the first entry index. determining, by the primary device, the second entry index based on importance of data in an entry corresponding to each index in the first entry index; wherein the determining, by the primary device, the second entry index based on importance of data in an entry corresponding to each index in the first entry index comprises: determining, by the primary device, the second entry index based on a quantity of access times of the data in the entry corresponding to each index in the first entry index.