What if Parallel HDF5 tests fail with a ROMIO error: File locking failed in ADIOI_Set_lock ... ?

This means that ROMIO, the MPI-I/O implementation used in mpich and openmpi and many other implementations, is attempting to use file locking when it is not supported by your file system. To resolve that, first you should attempt to rebuild your MPI library to disable file locking. This is the best way to resolve this error for your HDF5 application or any MPI-I/O application on your file system.

If that is not possible, there is a manual way to do this within your program. Unfortunately, this will require updating your programs and also updating the internal parallel HDF5 tests if you want them to succeed. The following steps are required:

• In your application code set "romio_ds_read" to "disable" and "romio_ds_write" to "disable" as hints in an MPI_Info object.

• Use this MPI_Info object to set the info parameter in every call to H5Pset_fapl_mpio(). Most likely this parameter was set to MPI_INFO_NULL.