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If you are working in batch mode, you must create this file using a text editor. However, for sake of simplicity it is recommended to let ANSYS create this file using interactive mode and then to proceed with batch mode operation. This file must reside in the directory where you are running ANSYS PDS. This file must include the following information:

•Remote hosts to be used for this particular parallel run.

•Number of processes that can run in parallel on each host. If a remote host has more than one CPU, you can use all of the CPUs on the remote host. For performance reasons, we recommend leaving one CPU for system tasks and using only N-1 CPUs for parallel processing (if N is the number of CPUs on the remote host).

•Directories in which you want the child processes to be executed. It is recommend that you use temporary directories like "/scratch" or "/tmp" on Linux or "C:\TEMP" on PCs. These remote directories are cleaned up automatically after the parallel processes finish running. Make sure that there is enough disk space in the directory for the files created by the analysis.

An example jobname.hosts file looks like this:

#This file is used to specify those hosts that the ANSYS Parent may

#run children processes on.

#

#Each host entry is to be on its own line. The host entry consists of

#several fields which are space delimited.

#

#Field 1 - host IP address or name

#Field 2 - username to use for a remote shell to the host

#Field 3 - execution key:

#0 - Use a remote shell to start the child process

#>1024 - Use a running ANSYS thin server on the host

#which is communicating on this port number

#Field 4 - the product code sequence to attempt to start ANSYS jobs

#on the host with. This is a colon delimited list.

#Field 5 - the number of jobs to run on this host

#Field 6 - The time in minutes to check again if the host is available.

#If this is zero then the host will not be checked again.

#Field 7 - If field 3 is nonzero then this is the local port number

#or range to start the communication with the ANSYS Thin

#Server on. This is tied to the "authentication" on the

#ANSYS Thin Server.

#If field 3 is zero then this should be set to zero.

#Field 8 - directory to create the children subdirectories in

#

#Example:

#UNIX box that has five processors and will first attempt to

#run with ANSYS Mechanical Batch Child and then ANSYS Mechanical

#zeus wjc 0 MEBACH:ANSYS 5 30 2000 /scratch/wjc

#XP box running the thin server on port 2010

#wjcpc wjc 2010 ANSYS 1 0 2000 C:\TEMP

alpha1 epc 0 MEBA:MEBACH 1 15 2000 /scratch/epc athena epc 0 MEBA:MEBACH 1 15 2000 /scratch/epc rs43p pdstest 0 MEBA:MEBACH 1 15 2000 /home/pdstest rs260 pdstest 0 MEBA:MEBACH 1 15 2000 /home/pdstest snoopy pdstest 0 MEBA:MEBACH 1 15 2000 /home/pdstest hp160 pdstest 0 MEBA:MEBACH 1 15 2000 /home/pdstest alpha24 pdstest 0 MEBA:MEBACH 2 15 2000 /home/pdstest hp770 pdstest 0 MEBA:MEBACH 1 15 2000 /home/pdstest us60 pdstest 0 MEBA:MEBACH 1 15 2000 /home/pdstest ss60 pdstest 0 MEBA:MEBACH 1 15 2000 /home/pdstest

1.3.9.3.2. Files Needed for Parallel Run

You also need to specify all other files that will be used in the distributed processing run. These files are listed in a separate file called Jobname.ifiles. At a minimum, this file must include the analysis

file. Additionally, you may need other files, such as data files or ANSYS macros. You must include all files that the analysis files calls in order for the PDS run to execute successfully. These files, which are typically found only on your local machine, will then be copied to all remote hosts during the PDS run. The Jobname.ifiles must reside in your working directory. If you are working in batch mode, you

need to create this file manually. The first file listed must be the analysis file. Other files listed must include the full path.

Command(s): PDANL

GUI: Main Menu> Prob Design> Analysis File> Assign

An example jobname.ifiles file looks like this:

#Files to copy to the ANSYS server for job Jobname

#created on Fri Oct 13 10:33:44 EDT 2000. pdsrun1.inp

/home/staff/epc/ddts/pds/tags

1.3.9.3.3. Controlling Server Processes

If you are working interactively, you need to complete one additional step. When you select Run Parallel, you see a dialog box listing all remote hosts specified in the Jobname.hosts file, as well as their current status. You can use this dialog box to specify a solution label, set the number of allowed failures (loops leading to an ANSYS error during execution) as well as monitor the processes and remote machines, and stop or start processes on those machines as necessary.

The number of allowed failures is used to automatically stop the parallel execution process if the number of loops leading to an error exceeds the allowed maximum number. In a typical case you don't expect your analysis file to cause an ANSYS error. If in this case there are several loops leading to an error, then this is most likely due to a bug in the APDL programming in the analysis file. Here, the ANSYS PDS automatically terminates the parallel execution if the number of allowed failures (loops with errors) exceeds the allowed maximum.

In certain cases however, you will know that executing the analysis file always leads to an error that can be ignored. An example is a non-linear burst analysis, which terminates with an error as the maximum displacement grows out of proportion. I.e. ultimately all loops will terminate with an error and the result of a burst analysis is the value of the load factor at which this instability happens. In this case you can force the ANSYS PDS to ignore the error and set the error flag in the result file to "0". To do this set the number of allowed failures in the exactly equal to the total number of loops. Since you are bypassing the error checking mechanism it is strongly recommended to thoroughly review of the probabilistic results in the file jobname_Slab.pdrs. It is not recommended to do this as a standard procedure, but only in cases where you are sure that the error generated in the analysis loop can be safely ignored.

The status codes you could see include:

•DOWN - The remote host is not available (reason unknown).

•DN-TS - The Thin Server is down.

•DN-DRF - ANSYS was unable to create the necessary directories on that host.

•DN-ANS - ANSYS would not start on that host.

•DN-ATH - Authentication failure (the batch child product was unable to authenticate with the parent product).