Huge “Network I/O” type resource waits

Posted: - Source : stackoverflow

We have an in-house application, developed in WinDev, that uses a Microsoft SQL Server 2012 SP2 (build 11.0.5058) database running on Windows Server 2008R2.

We are experiencing performance issues. At the same time Activity Monitor shows a huge number of waits of type "network I/O", where "huge" in this case is a cumulative wait time of 7 million seconds for a server that is up for less than 6 days:

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The network connectivity itself is fine, the server is connected with 10G while the client are either physical desktop connected with 1Gb or Remote Desktop servers with 10G. Network monitoring shows no link saturation, nor any other network issue. CPU, RAM and disk I/O are also fine.

From what I read about Network I/O waits, it relates to records returned by a query that are not consumed by the clients. So I tend to think the issue is in the application but I have a hard time having the developers investigate this (not that they are unwilling to do it, but they are quite busy and it seems they don't have any clue about the root cause and how to solve it)

So the questions:

  • Am I right thinking the performance issue is related to those Network I/O waits?

  • what clue could I provide to the dev team to help them identify the cause?

  • apart from fixing the application, is there some fine tuning I can do on the SQL Server itself to alleviate the issue?