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:
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:
3) If you already compiled the code with MPI, try to increase the number of cores used for the job.