More on SQL Server 2008 Connection Timeouts

A few more details on my current woes with SQL Server 2008. This is 64-bit Enterprise Edition, SP1 + CU5. We are getting severe, intermittent, but easily reproducible connection timeouts. This is when you attempt to connect to the instance, but the client eventually gets fed up of waiting and gives up, like this in Management Studio:-

 

This timeout is set by default in SSMS to be 15 seconds (plenty long enough to establish a connection to an instance on your LAN, Gigabit connected, fast server)…

This error is slightly different when you generate it using SQLCMD:-

 

I am getting other symptoms of the same underlying issue, e.g. occasionally when trying to read the error log in a query window using xp_readerrorlog:-

 

I have no resolution for this issue yet; will update if/when I do. Troubleshooting with Microsoft Premier Support has involved registry changes for things like Max Ports, chimneying off, SynAttackProtect (no benefit). We have also done network tracing using WireShark. I have done some testing with a custom Microsoft-supplied app, and also my own testing using SQLCMD. And before you asked, yes I have tried rebooting!! That’s not an easy thing to arrange when it’s a live 4-node cluster supporting 24X7 websites and applications… one of the (many) compelling reasons to have a passive node in your cluster, which you can use precisely for this kind of thing.

Wish me luck.. even the Director’s started asking for daily updates. Urgh!

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