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Strange network behavior causing problems

  • April 1, 2013 at 10:33 am

    #275927

    Hello everyone

    I'm trying to determine an odd problem and I have exhausted most of my capacity with no results... so I'm hoping someone has seen this before. I have both random connection problems and repeatable connection problems, and am not sure if they are related.

    I have 2 DB servers (windows 2008 r2, SQL2008 r2) set up with mirroring on my application databases with manual failover.

    I (was) running both systems on teamed adapters (4 network ports per server). 2 ports for the primary network (a vlan server only network), 1 port for a crossover between boxes (for the mirror), and 1 port to a physically isolated backup network (my big disk-to-disk-to tape system).

    A few weeks ago, I suffered a primary network switch failure. We put a replacement switch in place, loaded the vlan configuration, and went on with life. My application started to report random connection failures. These were not reproducible. I added the application server to my backup network (the one the DB is on), but the problem persisted. I then connected directly via crossover to my app box, and all is well for the application. But a crossover is not a long term solution; failover to the other box will require manual network cable moves. Furthermore, I have other systems that connect to this server via the vlan.

    Just yesterday, my BI box started having connection problems. I am able to reproduce it; connections *appear* to fail (using ssms connections to test), but ONLY as the service account user. And when it fails, it comes up with a "could not connect" message... but when you close the message, SSMS is actually connected fine.

    All of this started after a network switch failure. Switch has been replaced and is in use. I am not sure where else to look for causes to these connection problems 🙁

  • April 1, 2013 at 4:56 pm

    #1602638

    My application started to report random connection failures.

    We've had similar problems in the past. A good number of them turned out to be that the device was setup with "Auto-Negotiate" turned on. I recommend turning that off if it's on.

    --Jeff Moden

    RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
    First step towards the paradigm shift of writing Set Based code:
    ________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

    Change is inevitable... Change for the better is not.

    Helpful Links:
    How to post code problems
    How to Post Performance Problems
    Create a Tally Function (fnTally)

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