34.9.4 Parallel/Network/Configure...

The Parallel/Network/Configure... menu item opens the Network Configuration dialog box.

The ability to manually spawn additional compute nodes before reading the case file using the Network Configuration dialog box is only availabe when using the net option (e.g., -mpi=net). While this feature is still available in ANSYS FLUENT 6.3, its use is discouraged.

Network Configuration Dialog Box

Compute nodes are labeled sequentially starting at 0. In addition to the compute node processes, there is one host process. The host process is automatically started when ANSYS FLUENT starts, and it is killed when ANSYS FLUENT exits. It cannot be killed while running. Compute nodes, however, can be killed at any time, with the exception that compute node 0 can only be killed if it is the last remaining compute node process. The host process always spawns compute node 0. Compute node 0 spawns all other compute nodes.

If you want to spawn compute nodes on several different machines, or if you want to make any changes to the current network configuration (e.g., if you accidentally spawned too many compute nodes on the host machine when you started the solver), the Network Configuration dialog box allows you to control the configuration of your parallel network.

Parallel $\rightarrow$ Network $\rightarrow$ Configure...

Controls

Available Hosts   contains a selectable list of hosts available for creating a parallel machine. If the hosts file fluent.hosts exists in your home directory, its contents are automatically added to the Available Hosts list at startup. Hosts can be added to the list either by specifying a hostname and optional username in the Host Entry box, or by copying selected hosts from the Hosts Database dialog box.

Spawned Compute Nodes   contains the list of all compute node processes that form the parallel machine. Each entry lists the operating system, hostname, username, and compute node ID, in that order. Compute nodes can be added to this list by selecting hosts from the Available Hosts list.

Host Entry   is used to manually add and delete hosts from the Available Hosts list.

Hostname   is the internet name of a remote machine.

Username   is your login name on the machine specified in the Hostname field. If all your accounts have the same login name, you do not need to specify a username.

Spawn Count   defines the number of compute node processes to spawn on each selected host in the Available Hosts list.

Database...   opens the Hosts Database dialog box.

Connectivity   displays the network connectivity of all compute nodes selected in the Spawned Compute Nodes list. If no compute nodes are selected, the Parallel Connectivity dialog box is opened.

Add   adds a workstation from the Host Entry box to the Available Hosts list.

To add a host to the Available Hosts list manually, you can enter the internet name of the remote machine in the Hostname field under Host Entry, enter your login name on that machine in the Username field (unless your accounts all have the same login name, in which case you need not specify a username), and then click the Add button. The specified host will be added to the Available Hosts list.

Delete   removes the host specified in the Host Entry box or selected in the Available Hosts list from the Available Hosts list.

To delete a host from the Available Hosts list in the Network Configuration dialog box, select the host and click the Delete button. The host name will be removed from the Available Hosts list (but the Hosts Database dialog box will not be affected).

Save...   opens the Select File dialog box (see Section  2.1.6), which allows you to write a hosts file for future use that contains all entries in the Available Hosts list. In a future session, you can load the contents of this file into the Hosts Database dialog box and then copy the hosts over to the Network Configuration dialog box in order to reproduce the current Available Hosts list.

Spawn   creates compute node processes on all hosts selected in the Available Hosts list.

Kill   kills the compute node processes selected in the Spawned Compute Nodes list.

Remember that compute node 0 can only be killed if it is the last remaining compute node process.

The basic steps for spawning compute nodes are as follows:

1.   Choose the host machine(s) on which to spawn compute nodes in the Available Hosts list. If the desired machine is not listed, you can use the Host Entry fields to manually add a host, or you can copy the desired host from the host database.

2.   Set the number of compute node processes to spawn on each selected host machine in the Spawn Count field.

3.   Click the Spawn button and the new node(s) will be spawned and added to the Spawned Compute Nodes list.

Common Problems Encountered During Node Spawning

The spawning process will try to establish a connection with a new compute node, but if after 50 seconds it receives no response from the new compute node, it will assume the spawn was unsuccessful. The spawn will be unsuccessful, for example, if the remote machine is unable to find the ANSYS FLUENT executable. To manually test if the spawning machine can start a new compute node, you can type

rsh [-l username ] hostname fluent -t0 -v

from a shell prompt on the spawning machine. hostname should be replaced with the internet name of the machine on which you want to spawn a compute node, and username should be replaced with your login name on the remote machine specified by hostname.

If all your accounts have the same login name, you do not need to specify a username. (The square brackets around -l username indicate that it is not always required; if you do enter a login name, do not include the square brackets.) Note that on some systems, the remote shell command is remsh instead of rsh.

The spawn test could fail for several reasons:

Login incorrect.   The machine spawning a new compute node must be able to rsh to the machine where the new process will reside, or the spawn will fail. There are several ways to enable this capability. Consult your systems administrator for assistance.

fluent: Command not found.   The rsh to the remote machine succeeded, but the path to the ANSYS FLUENT shell script could not be found on that machine. If you are using csh, then the path to the ANSYS FLUENT shell script should be added to the path variable in your .cshrc file. If that also fails, you can use the parallel/network/ path text command to set the path to the Fluent.Inc installation directory directly before spawning the compute node.

parallel $\rightarrow$ network $\rightarrow$ path