1) Your machine does not have enough memory to run real.exe on your domain
2) If your machine has enough memory and multiple CPU's, but a single CPU cannot access all the memory, you need to build WRF with the dmpar (MPI) option and run it on multiple processors (mpirun -np N real.exe, where N>1) to utilize more of the available memory. See this FAQ:
http://forum.mmm.ucar.edu/phpBB3/viewtopic.php?f=73&t=127
3) If you already compiled the code with MPI, try to increase the number of cores used for the job.
2) If your machine has enough memory and multiple CPU's, but a single CPU cannot access all the memory, you need to build WRF with the dmpar (MPI) option and run it on multiple processors (mpirun -np N real.exe, where N>1) to utilize more of the available memory. See this FAQ:
http://forum.mmm.ucar.edu/phpBB3/viewtopic.php?f=73&t=127
3) If you already compiled the code with MPI, try to increase the number of cores used for the job.