Parallel File Systems (PFS) luster Glusterfs GPFS

Different Linux File System types | Parallel File System (PFS) | Lustre, Glusterfs and IBM GPFS | DFS 

Parallel File Systems (PFS) store application data persistently usually extremely large datasets that can't be store in normal memory PFS provide global shared namespace file, directories.

PFS supports parallel applications, where all nodes access the same files at the same time "concurrently reading" and writing, Data for a single file which striped across multiple storage nodes to provide scalable performance to individual files. mostly PFS used on level enterprise shared storage system. 

PFS designed for parallelism,  as PFS allow concurrent access from many clients in HPC environment.

PFS designed for high performance computing operate over high-speed network called InfiniBand, Myrinet, Portals on optimized I/O path for high speed bandwidth. 

PFS distribute data of a single object across multiple storage nodes. PFS run on architectures storage which are physically separated from the compute system. 

PFS target HPC (High Performance Computer) applications which tend to perform highly coordinated I/O accesses, and have massive bandwidth requirement, Lustre, Glusterfs and IBM GPFS are example of PFS. 
Distributed file system (DFS) 

Distributed file system often store entire object (files) on a single storage node. Distributed file system often run architectures storage physically separate from the compute system. Distributed file system take on fault-tolerance responsibilities. Distributed file system are geared for loosely coupled distributed application.