ABSTRACT
Iota is a lightweight tracing tool for diagnosing poorly performing I/O operations to parallel file systems, especially Lustre. It collects complete traces of POSIX I/O calls with minimal overhead, and has been tested to scale to 110,052 MPI tasks and 1.5 TB of data. Iota is freely available under a noncommercial license from:
https://bitbucket.org/mhowison/iota
As the storage systems and the parallel file systems that service supercomputers become more complex, it is increasingly important to have finely tuned tracing tools for investigating poor I/O performance. The POSIX I/O layer is often informative because it is the interface between user-space code (either the application itself or a middle-ware library like MPI-IO or HDF5) and a kernel-space parallel file system.
