Server directed file domain allocation for noncontiguous file access

Parallel I/O systems frequently use collective I/O to improve the performance of applications that have small and noncontiguous data access patterns. The performance of a collective I/O implementation depends on how well its I/O libraries and parallel file system cooperate. We present a novel server directed file domain allocation (SDFDA) approach motivated by a study of interaction between MPICH/ROMIO and PVFS for noncontiguous file access. In our SDFDA approach, the file domains are bound to processes, according to the data layout scheme of I/O servers, as well as the number and placement of the ROMIO aggregators. We conducted an empirical study on an MPICH/PVFS cluster platform and compared the performance of our SDFDA approach with the existing ROMIO allocation approach. The results show that by providing a light correlation between MPICH/ROMIO and PVFS, our approach conforms I/O distribution to PVFS file striping and achieves higher performance improvement for noncontiguous file access.