Intermittent Connection Problems to SQL 2005

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Intermittent Connection Problems to SQL 2005

Steve-443559

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December 13, 2010 at 8:55 am

#232024

Every once in a while (maybe once a month at no regular time), I get a message from the biztalk application servers
An attempt to connect to "BizTalkMsgBoxDb" SQL Server database on server "Server30.ap.org" failed.
Error: "[DBNETLIB][ConnectionOpen (Connect()).]SQL Server does not exist or access denied."
And recovers in less than a minute or two. This happens on all servers in the biztalk application farm so it probably has something to do with the SQL Server itself. There are no errors on the SQL Server and no alerts from SCOM (Which would have thrown something off if it couldn't connect or our other monitoring utilities. No blocking alerts.
What steps can I take to figure out what is causing this? I can't reproduce it and it comes and goes to quick for me to start something once the issue occurs. Some kind of trace maybe?
Thanks,
Steven

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Kory Becker Hall of Fame Points: 3585 More actions · Answer 1

Is the SQL Server on a cluster?

Is the client conection to the server using a port or \\<host>\<dataserver>?

Steve-443559 SSCrazy Points: 2309 More actions · Answer 2

It's connecting using the Servername, which resolves to the IP address (presumably, during this time). It is the default instance using the standard SQL port.

Thanks,

STeven

Kory Becker Hall of Fame Points: 3585 More actions · Answer 3

Is the data server on a cluster?

What version of sql server are you running?

Try to use <host>, <port> in the client connection to remove the sql browsing service as a possible cause.

Kory Becker Hall of Fame Points: 3585 More actions · Answer 4

Also when the issue occurs capture the netstat output to see what is using port 1434.

Steve-443559 SSCrazy Points: 2309 More actions · Answer 5

This is a SQL 2005 Standard x64 instance on a windows 2003 Enterprise x64 Cluster. I'll try changing the connection to use Servername,Port - although, since it's using the default instance, it wouldn't be using SQL Browser, would it?

I'll also run a netstat on client and server.

Thanks so much for your help.

Kory Becker Hall of Fame Points: 3585 More actions · Answer 6

Yes, when the defualt port is being used SQL Browser is not used as it looks directly for port 1433.

Kory Becker Hall of Fame Points: 3585 More actions · Answer 7

I trust the host being used is the cluster name not a node, correct?

Steve-443559 SSCrazy Points: 2309 More actions · Answer 8

Yes, it connects to the SQL Cluster name. It works fine most of the time, just for an intermittent span of 1-2 minutes. I don't see any performance counters out of the ordinary during this time (CPU, Network, etc.). I don't get any alerts for blocking.

Kory Becker Hall of Fame Points: 3585 More actions · Answer 9

Can you correlate the errors to any events on your firewalls, DNS, or WINS?