  For an increasing number of data intensive scientific applications, parallel
I/O concepts are a major performance issue. Tackling this issue, we develop an
input/output system designed for highly efficient, scalable and conveniently
usable parallel I/O on distributed memory systems. The main focus of this
research is the parallel I/O runtime system support provided for
software-generated programs produced by parallelizing compilers in the context
of High Performance FORTRAN efforts. Specifically, our design aims for the
Vienna Fortran Compilation System.
  In our research project we investigate the I/O problem from a runtime system
support perspective. We focus on the design of an advanced parallel I/O
support, called ViPIOS (VIenna Parallel I/O System), to be targeted by language
compilers supporting the same programming model like High Performance Fortran
(HPF). The ViPIOS design is partly influenced by the concepts of parallel
database technology.
  At the beginning of the project we developed a formal model, which forms a
theoretical framework on which the ViPIOS design is based. This model describes
the mapping of the problem specific data space starting from the application
program data structures down to the physical layout on disk across several
intermediate representation levels.
  Based on this formal model we designed and developed an I/O runtime system,
ViPIOS, which provides support for several issues, as - parallel access to
files for read/write operations, - optimization of data-layout on disks, -
redistribution of data stored on disks, - communication of out-of-core (OOC)
data, and - many optimizations including data prefetching from disks based on
the access pattern knowledge extracted from the program by the compiler or
provided by a user specification.
