Abstract: An aspect of the invention is directed to a plurality of MDSs (metadata servers) in a distributed storage system which includes data servers storing file contents, each MDS having a processor and a memory and storing file system metadata. Directories of a file system namespace are distributed to the MDSs through referral directories referring to real directories using hash value of inode number of each of the referral directories. During a process to create a directory in the file system namespace, a first MDS dynamically creates a referral directory in the first MDS, and creates a real directory in a second MDS, the referral directory in the first MDS referring to the real directory in the second MDS by maintaining location information of the real directory in the second MDS, the real directory in the second MDS containing the file system metadata for the directory in the file system namespace.