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I have a question regarding the number of concurrent sessions


Ivan Hancock

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Hi all,

I have a question regarding the number of concurrent sessions. If I am going SFTP -> MFT IS -> SFTP, within the application, is there a way of controlling the number of concurrent sessions a source can establish or is this all controlled by the SSH config on the boxes

We are running IS 7.2.4.

Thanks

Ivan

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Thanks for bringing this up Ivan. One of the issues that we have found here is at times if you have certain transfer definitions in place wherein you are supposed to get a file transferred from IS to another external server (SSH or SFTP); then depending on the number of times the transfer definition has triggered the number of connections to the external server will go up. Now in a typical Linux/UNIX environment you have ulimits set at an OS level. For instance, if the number of open files per process is set to 1024 then IS will be able to open max 1024 connections and these are the entries as part of file descriptors. Beyond the same, one may get "Too many open files" error.

In certain organizations increasing ulimits may not be suitable hence there needs to be a way to handle such TCP connections. Is there really a configuration (as part of web.xml or server.xml) which could be used

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Thanks for this, but I was more interested in understanding if it can be controlled on a server by server basis rather than in it's entirety. For example, what is there to stop one source opening 1000's of concurrent connections. In Connect:Direct for example you have a max sessions parm per node that controls the number of available sessions. Is there similar limiting config in IS or is it just controlled at this higher level
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With IS, if you have multiple nodes, they share the same back end database that controls the various send/receive server/transfer/user information. The server.xml file is specific to that machine and is configured independent of each other. So, yes, it is on a server by server basis. The maxConnections tomcat parameter will limit the number of simultaneous sessions once it is configured. All server.xml parameters are on a server by server basis. There is also lockout rules that can be done (which involve failed password attempts) on a more global level.
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Satyakam, I can't say for sure, that is probably more of a support ticket type of question. "too many" is a very observational type of comparison. I would check the settings on the transfer definitions and see if there is pooling in place. That's the only thing I can think of at the moment. I haven't observed any impact from "close_wait" status connections on any of my machines.
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I have seen instances of connections in a close wait state, but we have been unable to determine the cause of this.

I suspect it may be due to idle connections being terminated.

I suggest setting the SSH Pooling Idle Timeout to 10 (default is 30) minutes

I suggest setting the FTP Pooling Idle Timeout to 10 (default is 30) minutes

In these cases, MFT will terminate the connections before a firewall terminates them.

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  • 2 years later...

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