Parallel Virtual File System

The Parallel Virtual File System (PVFS) is an open source parallel file system. A parallel file system is a type of distributed file system that distributes file data across multiple servers and provides for concurrent access by multiple tasks of a parallel application. PVFS was designed for use in large scale cluster computing. PVFS focuses on high performance access to large data sets. It consists of a server process and a client library, both of which are written entirely of user-level code. A Linux kernel module and pvfs-client process allow the file system to be mounted and used with standard utilities. The client library provides for high performance access via the message passing interface (MPI). PVFS is being jointly developed between The Parallel Architecture Research Laboratory at Clemson University and the Mathematics and Computer Science Division at Argonne National Laboratory, and the Ohio Supercomputer Center. PVFS development has been funded by NASA Goddard Space Flight Center, Argonne, NSF PACI and HECURA programs, and other government and private agencies. PVFS is now known as OrangeFS in its newest development branch.

PVFS was first developed in 1993 by Walt Ligon and Eric Blumer as a parallel file system for Parallel Virtual Machine (PVM) as part of a NASA grant to study the I/O patterns of parallel programs. PVFS version 0 was based on Vesta, a parallel file system developed at IBM T. J. Watson Research Center. Starting in 1994 Rob Ross re-wrote PVFS to use TCP/IP and departed from many of the original Vesta design points. PVFS version 1 was targeted to a cluster of DEC Alpha workstations networked using switched FDDI. Like Vesta, PVFS striped data across multiple servers and allowed I/O requests based on a file view that described a strided access pattern. Unlike Vesta, the striping and view were not dependent on a common record size. Ross' research focused on scheduling of disk I/O when multiple clients were accessing the same file. Previous results had shown that scheduling according to the best possible disk access pattern was preferable. Ross showed that this depended on a number of factors including the relative speed of the network and the details of the file view. In some cases a scheduling based on network traffic was preferable, thus a dynamically adaptable schedule provided the best overall performance.