The basic requirements and restrictions for running any model with MPI were discussed under MPI on a Single Machine. This page focuses only on setting up the Windows cluster option, which allows a model to be run across multiple computers simultaneously. This option requires the main node where the model is set to run and any number of worker nodes. The configuration of this kind of system is relatively complicated and will likely require the support of an IT administrator. The setup requirements are described below. Guiding principles for domain decomposition for running MPI are also provided here.

1. Requirements for All Computers on a Cluster (Main & Worker Nodes)

> whoami
Next, invoke the following commands to set up the Hydra process manager:
> hydra_service -start
(Note: In some cases, the Hydra_service may automatically start, the user can ignore the error that it cannot start because it already running)
> mpiexec -register
(Enter the domain-name\username from the previous step)
confirm password
> mpiexec -validate

2. Configuration for Main Node

Figure 1 Share working directory from the Main Node (1).

3. Configuration for Worker Computers

Figure 2 Share working directory from the Main Node (2).

In this example, the model folder on the main node is "E:\EFDC_Explorer Modeling System\Testing\EFDC\MPI_Model" so the user should create a folder path as "E:\EFDC_Explorer Modeling System\Testing\EFDC\" on the worker computers. Note that there no need to create the folder name "MPI_Model", otherwise the next steps will have an error.

General case: Mklink /d "Working-Directory" "Shared-Directory"
In this example: mklink /d "E:\EFDC_Explorer Modeling System\Testing\EFDC\MPI_Model" "\\DSI-D03\MPI_Model"

Figure 3 Run as Administrator for Command Prompt (1).

Figure 4 Run as Administrator for Command Prompt (2).

4. Steps to Configure EEMS to Run EFDC+ MPI

After setting up the cluster to run the model, running MPI on a cluster is the same for an MPI run on a single PC.
From EE main menu the click EFDC+ Run button and the EFDC+ Run Options form will be displayed. The tabs for General and MPI Cluster must be configured as described below.
General Tab

Figure 5 EFDC+ Run Options: General tab.

5. MPI Cluster tab Settings

Figure 7 EFDC+ Run Options: MPI Cluster tab.

Figure 8 EFDC+ Run Options: MPI Cluster tab.

Figure 9 Example Host file.

Figure 10 EFDC+ Running.