Murmur Hash 2 is a Murmur Hash family algorithm invented in 2009 by Austin Appleby . It is mainly used in libstdc++ (ver 4.6), libmemcached, maatkit, Hadoop, Kyoto Cabine.
The digest (hash generated by this algorithm) is 32 bits (4 Bytes) in length.
You can read more about it on this page.