On Tue, Dec 14, 2010 at 8:08 AM, Quincey Koziol <[email protected]> wrote: >> If not, there is another optimization that I think was reported in a >> paper on PLFS or Adios about passing a flag to the fopen call on each >> MPI task that tells it not to update the creation/modification time >> except on the root task. This can greatly reduce the load on the >> metadata server for a parallel file system. > > Interesting, can you send me a reference for this?
I'm pretty sure the trick was to use O_NOATIME in the open() call, except on task 0. (You can find this on NICS webpage on I/O best practices.) I know I came across it in the lit review for our HDF5/Lustre paper, but I can't put my fingers on the paper. It might haveI vaguely recall a scaling graph showing how this outperformed a regular open() call, and I think the text was 1-column wide... I'll keep looking through my woefully unorganized pile of PDFs. Mark _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
