Embodiments of the present invention provide methods, systems, and computer program products for data deduplication. In one embodiment, for a data chunk, it is determined whether a hash value of the data chunk generated by a first hash function is present in a hash table. Once a threshold size of the hash table is reached, it is determined whether there is free space in a write data area, identified by a second hash function. When there is no free space in the write data area, a post-deduplication process is performed for each data chunk in the write data area. Once free space is cleared in the write data area, the data chunk is written to the write data area identified by the second hash function.