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Old 07-14-2009, 04:23 AM   #1
Registered: Jun 2005
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Samba - prevent locking of selected files over network?

I have a samba server which is serving a mixture of files. One main application uses a data file and creates a temporary working execution file at startup and holds that temp execution file open for the duration of the program's execution (but doesn't use the file at all after initial startup).

The problem is when a second user wants to run the application (and they all do) they cannot create/replace the temp file because it is file locked over the network by the other running copy of the application, despite the application not using it any more. The application is a long running program, we're talking hours at a time.

This results in us having to remove the file from the unix file system manually at user request so the next user using the application against the share succeeds in creating the temp file and starting up.

So the question is, is it possible to selectively disable file locking over the network in samba (preferably by regex)
Old 07-15-2009, 05:41 PM   #2
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I believe that the better approach is to look at the application. Why is it creating the lock file? (That's what this sort of thing is called. It's an old UNIX technique for file sharing.) The lock file could be trying to protect a data file. If that is the case then removing the lock file by hand to allow additional instances of the application to access the same shared directory could be a mistake. You could be courting data corruption.

If that is not the case then why was the application designed to create this lock file?

If deleting the lock file is totally harmless then maybe you could configure the application to stop creating the file or to create the file on the client where it is running. Find out if it is using an environment variable to determine the location of the lock file. Maybe you could manipulate that such as defining it readonly to point to a local directory such as $HOME/tmp.
# FILE: .bashrc
readonly TMP=$HOME/tmp
export TMP
You may be able to do something similar with whatever environment variable this application uses, if any.

If the location of the lock file is hard coded into the application then this approach won't work. In that case I would again suggest that you consider whether this lock file may be doing something useful. If the lock file is not doing anything useful then the application designer made a strange decision.
Old 07-16-2009, 04:46 AM   #3
Registered: Jun 2005
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It's not a unix app and it's not a lock file. It's a windows app running on a file over a samba share and creating a program execution plan file next to the file it is using. The file is not needed after the initial startup of the long running process.

Hence why we go and delete it from the unix side so a different client can start the program on the same file...

Data corruption is not an issue in this case.


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