Parallel Software for Processing Hydrographic Data

The Naval Research Laboratory's (NRL) Code 7440 Production Enhancement Team at the Stennis Space Center has been tasked to develop ways to speedup hydrographic data processing at the Naval Oceanographic Office (NAVO). This paper presents the final development of a parallelized version of the Pfm_loader application customized to run on a Beowulf cluster. Parallel programming techniques have been used for years to develop processing software that does the same work in only a fraction of the time. The research in this paper focuses on the I/0 problem associated with a parallel application writing to a single physical disk. Included in our research are the original ideas that led to the first version of the parallel software, subsequent versions of the software derived from lessons learned from benchmark results, and speedup results of each version. The platform used was a custom built Linux Beowulf cluster running a standard Linux kernel and the MPICH parallel message-passing library. The underlying purpose of this software is to process hydrographic data having a complicated, multi-tiered format. The data processing involves reading tens to hundreds of files containing raw date, filtering out extraneous data values, and writing the filtered data to a single file used in additional processing. The problem is not computationally intensive, but bound by the system's file writing capability. Subsequent versions of the parallel software developed exploit the strengths of the system's hardware to write the output file in the most time efficient manner. Each software version uses advanced software architecture schemes to achieve better results. Results show that the more responsible the software was for organizing the data before writing, the better the speedup. The critical factor for writing data efficiently involved the limitation of writing data over a single I/0 controller. Our parallel software has fantastic utility where system specifications do not allow for the 7 The original document contains color images. All DTIC reproductions will be in black and white.