Embodiments of the present disclosure disclose a solution for data backup and recovery in a storage system. When a source device in the storage system backs up, to a backup-end device, a data block that is written after a snapshot Sn, the source device performs a logical operation such as an exclusive-NOR or exclusive-OR operation on the written data block and an original data block, which is recorded in the snapshot Sn, of the written data block, and then compresses a data block obtained after the logical operation, which improves a compression ratio of a data block, thereby reducing an amount of data that is sent to the backup-end device, and saving transmission bandwidth. The solution may be further applied to a scenario of data recovery in a storage system.