  Practitioners of lattice QCD/QFT have been some of the primary pioneer users
of the state-of-the-art high-performance-computing systems, and contribute
towards the stress tests of such new machines as soon as they become available.
As with all aspects of high-performance-computing, I/O is becoming an
increasingly specialized component of these systems. In order to take advantage
of the latest available high-performance I/O infrastructure, to ensure
reliability and backwards compatibility of data files, and to help unify the
data structures used in lattice codes, we have incorporated parallel HDF5 I/O
into the SciDAC supported USQCD software stack. Here we present the design and
implementation of this I/O framework. Our HDF5 implementation outperforms
optimized QIO at the 10-20% level and leaves room for further improvement by
utilizing appropriate dataset chunking.
