db connections broken from time to time for unknown reason, please help!

  • I am having a strange problem with my database connections from Query Analyzer (QA) and Enterprise Manager (EM) to one database server. those connections all break from time to time, on average every 3-5 minutes. Symptons:

    1. in EM, error pops out saying "connection to SERVER1 broken, do you want to try to reconnect it?"

    2. in QA, similar message when clicking a db object such as a table, "could not find the object, it may have been dropped or recreated. Refresh at a higher level. "

    3. On the server, when I issue  T-SQL command "SELECT * FROM master..sysprocesses WHERE hostname = 'my_workstationname' ", the previous records indicating connections are gone.

    Here are the steps that I have tried:

    1. ruled out connection problem from my workstation to intranet, because it happens only to one particular server, connection to other  db servers don't have that problem.

    2. Tried windows command "ping -t SERVER1" for more than 15 minutes but didn't see the command stop (always ping-able)

    3. The DBA sitting next to me doesn't have that problem for the same server - His connections to that server remains when all my connections are broken by checking "SELECT * FROM master..sysprocesses WHERE hostname = 'my_workstationname' ". We are on the same subnet.

    It happens to my QA, EM, and another SQL editor called "Apex SQLEditor" that I use.

    Any thoughts?

  • Check with your network manager.  The port you are connected to on the switch may be bad.  Also check your patch cable.  My hunch is a bad port on the switch.

    Good luck

    Marvin

    Marvin Dillard
    Senior Consultant
    Claraview Inc

  • I don't think this is a switch. Raymond says it pingable all the time without interruptions. But is is good to test. Why don't Raymond plugs in his computer to his next-sitting DBA's network cable and see what happens. If he still gets an error it is probably something on his computer. Maybe a connection timeout (??? not really relevant) or the other app?

    Regards,Yelena Varsha

  • Trading network connections with the DBA next to you would let you rule out, or in, a hardware issue with your network. 

    So long, and thanks for all the fish,

    Russell Shilling, MCDBA, MCSA 2K3, MCSE 2K3

  • Thanks for all the advice. I traded the network connections with the other DBA, but the problem persists.

    However, this time, I noticed that my connection from Enterprise Manager (EM) stays, while connection from QA and QA - object browser were lost as before. So are the connections established by the 3rd party SQL Editor.

    Since SQL Editor uses disconnected connections to the database server, which I guess it dropped db connections when the connection remain inactive for a certain period of time. This makes me think there might be a bug in that tools which mistakenly dropped connections established by QA. But I am not 100 percent sure about that, because yesterday I rebooted my machine and tested without that tool running, but connections were dropped as usual. But I can't rule this out because I am the only DBA using that tool and the only one experiencing that problem.

    I will contact the author of the tool to see if the problem could possibly be related to his tool.

    Raymond

  • Raymond,

    That was a good test. The fact that the tool was not running at the time of your test tels nothing unless you are sure NO Background processes fro that tool are running that "take care" of your connection. Or maybe something in the registry. Try to uninstall the tool and see what happens. It is not a 100% pure test, it is only as good as the tool uninstall program is good. But worth a try. The "better" test will be to instll the tool on another test computer and see what happens. But it may corrupt this second computer also it it is at fault.

    Yelena

     

    Regards,Yelena Varsha

  • You've tried cable switching. You're looking at the 3rd party software vendor)have you un-installed it yet ?). Regsitry, well thats everyone's own choice ... How about NIC settings. I've had this as an issue on IBM E-series servers and  on some HP equipment as well. Sometimes 'auto' for detection of mode and speed need to be set explicitly.; You should check with your network person on the allowable port settings for your machine however (mis-setting these could also be the cause as well). Additionally, the NIC card could be bad as well. However 'cracking' the case open is the last resort. I'd remove the 3rd party software, then try the NIC configuration changes then as a last resort chaneg the nIC card.

    RegardsRudy KomacsarSenior Database Administrator"Ave Caesar! - Morituri te salutamus."

  • Rudy,

    When you say NIC setting, you meant the NIC of my computer, or the NIC of the server? My computer is an IBM R40 laptop, while the server is an HP NetServer running on Windows 2000 Advance Server version. I tried change the NIC setting of "detect" fro "auto" to "100MB full duplex", but it doesn't seem to fix the problem.

    I got in touch with the author of that 3rd-party tool, interestingly, he is having the same problem with his machine. He tends to think it is not a problem of that tool because "we both experienced the same problem when the tool is not running". But, you guys are right, the tools is not running doesn't mean it will not affect the connection on, but it is hard to ping down exactly what reg key that the tool introduces or changes may have affected the sql connection.

     

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