@Article{mackay:groundwater, author = {David Mackay and G. Mahinthakumar and Ed D'Azevedo}, title = {A Study of {I/O} in a Parallel Finite Element Groundwater Transport Code}, journal = {The International Journal of High Performance Computing Applications}, year = {1998}, month = {Fall}, volume = {12}, number = {3}, pages = {307--319}, keywords = {parallel I/O application, pario-bib}, abstract = {A parallel finite element groundwater transport code is used to compare three different strategies for performing parallel I/O: (1) have a single processor collect data and perform sequential I/O in large blocks, (2) use variations of vendor specific I/O extensions (3) use the EDONIO I/O library. Each processor performs many writes of one to four kilobytes to reorganize localdata in a global shared file. Our findings suggest having a single processor collect data and perform large block-contiguous operations may be quite efficient and portable for up to 32 processor configurations. This approach does not scale well for a larger number of processors since the single processor becomes a bottleneck for gathering data. The effective application I/O rate observed, which includes times for opening and closing files, is only a fraction of the peak device read/write rates. Some form of data redistribution and buffering in remote memory as performed in EDONIO may yield significant improvements for non-contiguous data I/O access patterns and short requests. Implementors of parallel I/O systems may consider some form of buffering as performed in EDONIO to speed up such I/O requirements.}, comment = {In a Special Issue on I/O in Parallel Applications, volume 12, numbers 3 and 4.} }