### 3.2.1. Host Configuration Set to Run Autodyn in Parallel

To run Autodyn in parallel, you must define the host machine configuration you wish to use. Autodyn allows you to define up to ten host configuration sets and select one of these sets as the active configuration.

Host configuration set data is saved in an external file called parallel.cfg, located in your running directory. This is a text file that must be edited manually.

Here is an example of the typical contents of this file.

    #@EPDEF=\\host1\autodyn (1)
    #@PPDEF office (2)
    #@PPCFG office (3)
    host1 sp=1000 (4)
    #@ mem=128 cpu=1 task=1 (5)
    host2 sp=500 ep=\\host2\autodyn (6)
    #@ mem=256 cpu=2 task=2 (7)

(1) Defines the default path for the Autodyn master and slave executables (autodyn.e182 and adslave.e182) to be \\host1\autodyn , where autodyn is a shared directory on host1. When the master and slave executables reside in the directory /usr/ansys_inc/v182/autodyn/bin/linx64, the share \\host1\autodyn should point to that directory.

(2) Defines the configuration set name that is to be used (office).

(3) Indicates that the following lines, until the next `#@PPCFG` statement, defines configuration set office. (There is only one configuration set defined in this example.)

(4) Adds host1 to configuration set office. It has a relative speed of 1000 and uses the default path for the Autodyn executable (since no `ep` parameter is defined).

(5) Specifies host1 has 128 Mb of memory, 1 CPU, and is to have 1 task (slave process) started on it.

(6) Adds host2 to configuration set office. It has a relative speed of 500 and /autodyn as the path for the Autodyn master and slave executables.

(7) Specifies host2 has 256 Mb of memory, 2 CPUs, and is to have 2 tasks (slave processes) started on it. The operating system will automatically allocate 1 task to each CPU.

The parallel.cfg file is an external file that is read whenever a project is executed in Autodyn. Host configuration sets are therefore not project dependent (unlike the domain decomposition sets described in the next chapter). When you create or modify a host configuration set while working on a particular project, that set becomes available for all projects.

When an Autodyn analysis is started using the command script `autodyn182`, the host configuration set defined in the parallel.cfg file is read, applfile is generated automatically and `mpirun` is started (similar as is done on Windows operating systems).

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