The best way to write code to take advantage of the tremendous speed potential of PVFS2 is to use MPI-IO. ROMIO has been updated to readily use PVFS2. The various hints and data access techniques within ROMIO have been updated to use PVFS2 to the fullest extent possible. This change makes a lot of sense since MPI-IO is part of the MPI-2 standard and is not supposed to change from vendor to vendor.

In addition to MPI-IO, there will be a library for interacting with PVFS2. However rather than have I/O functions that are very close to the UNIX/POSIX I/O functions, these are likely to be closer to the VFS functions that PVFS2 needs for speed and scalability. The difficulty for most people will be the lack of familiarity with the VFS functions in Linux. The best suggestion that Dr. Rob Ross, the lead developer of PVFS2 gives is to, "... suggest that people write serial tools to the UNIX I/O API and parallel ones to the MPI-IO API; that will get them both the best overall performance in the parallel case and the best portability in both cases."

This article was originally published in ClusterWorld Magazine. It has been updated and formated for the web. If you want to read more about HPC clusters and Linux you may wish to visit Linux Magazine.

Dr. Jeff Layton hopes to someday have a 20 TB file system in his home computer. He lives in the Atlanta area and can sometimes be found lounging at the nearby Fry's, dreaming of hardware and drinking coffee (but never during working hours).