On 06/21/2016 12:48 PM, Jon Povich wrote:
I'm trying to simulate a cluster setup where only the I/O aggregators have access to the working directory. Is this feasible to do with romio hints?
Setup: A) Work dir is on Node0's local hard drive. B) Remote Node1 has no access to Node0's hard drive C) Run a case where only rank 0 on Node0 serves as the I/O aggregator
that should work as long as you only use collective operations. You'll trigger the "deferred open" optimization. https://press3.mcs.anl.gov/romio/2003/08/05/deferred-open/ Your hints are close.
MPI_Info_create(&info); MPI_Info_set(info, "cb_nodes", "1"); MPI_Info_set(info, "no_indep_rw", "true");
The hint is actually "romio_no_indep_rw". Where did you find "no_indep_rw" documented? I'd like to get that fixed. I'd adjust one more hint: the "cb_config_list" hint. By default it is "*:1", which means select one MPI process from each node to act as aggregator. That's *probably* node0/crane/whatever, but you can ensure the desired node is selected by being more explicit. I'd make your cb_config_list look like "crane:1" or "node0:1" or whatever MPI_Get_processor_name returns. In 2014 we went on a deferred open cleanup and fixed a few bugs. I hope you are using MPICH-3.1.3 or newer. ==rob _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss