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-   -   Slow networking Windows FileServer - Linux CFX12 (http://www.cfd-online.com/Forums/cfx/70907-slow-networking-windows-fileserver-linux-cfx12.html)

Arjan December 9, 2009 10:58

Slow networking Windows FileServer - Linux CFX12
 
I have a very perculiar problem with the datatransfer between CFX12 installed on a Linux machine (SUSE 11.0) and a cifs (samba) mount on this machine of a shared map on a Windows server (the fileserver). These are the symptoms:

- In CFX12-Solve loading a .def file from the fileserver takes several tens of minutes instead of the usual (split) seconds. (I've compared it)

- In CFX12-Pre saving or loading a .def or .cfx file also takes tens of minutes.

- In CFX12-Pre, when I've started a new case and import a .cfx5 (mesh) file, no extra time is taken.

- When files are stored locally or on a mount referring to an other linux machine, there are no problems using CFX12. This indicates there is a problem between the cifs mount and CFX12.

- When making a symbolic link to the .def file on the fileserver (thus to the file in the mounted directory) and store this locally, everything works normal. However, making a symbolic link to the whole directory does not work.

- CFX11 works normally.

- CFX12 installed on a windows computer works normally.

- Every other way of using the cifs mount on the linux machine doesn't pose any problems.

I have posed this problem to CFX support, but they suggest it has to do with the license server. I disagree with this since CFX12 does work in certain circumstances.

I have no clue on where to search for a solution for this problem. The setup of the mount and CFX seems all normal to me. Are there any special options I should know about? Has anyone experienced the same problem?

Arjan December 18, 2009 04:48

FYI:

After an long email discussion with ansys support, the problem seems to be located. Quoted from an email:
"Although I'm still waiting for a formal response from the developer responsible, I'm reasonably sure about what the cause of this problem is. When either a .cfx or .def file is opened, various temporary lock files are also created to signal to other ANSYS applications that the file is in use. The handling of these lock file was changed between CFX-11.0 and CFX-12.0 and now uses a particular C function (if you're interested it's mkstemp). However, the use of this function appears to interact badly with CIFS mounts. It looks as though there can be up to a 60 second timeout (i.e. delay) whenever one of these files is opened. This would cause this problem, as the .cfx and .def files are opened and closed a number of times when being written by CFX-Pre."

They are going to try to fix it in a future version. However for now no real workaround exists. When there is, I'll post it.


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