So I’m fighting an issue at the office that is VERY annoying.

So I’m fighting an issue at the office that is VERY annoying.  It’s an intermitent slight drop of network connections, not enough that I lose ping, but enough that my tax software, and my other database style programs “drop”.  It occurs around 5ish to 6ish p.m. yet I’ve moved all of my backup windows away from that.


HP ProLiant ML370 G6 Server series –  HP NC-Series QLogic nx3 Multifunction Driver for Windows Server 2008 R2 – HP Business Support Center:
http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=15351&prodSeriesId=3884310&swItem=MTX-773f6bf1a1e345e7a2cdbd3b1d&prodNameId=3884311&swEnvOID=4064&swLang=13&taskId=135&mode=4&idx=3

I thought it might be that … note the “issues with virtual machines”.  But it occurred tonight again.  Now here’s a kicker, I have a VMware machine that I run Quickbooks 2006 on and I’m working on an older version today.  In my Vista machine I was running Quickbooks 2008.  The outside Quickbooks dropped the connection.  The inside XP Quickbooks did not. 


QuickBooks Support – Error: “Connection Has Been Lost” when working on a company file:
http://support.quickbooks.intuit.com/support/Pages/KnowledgeBaseArticle/829e206e

So the virtual did not drop the connection like that, the real computer did.  There are days like this that I really do hope the cloud delivers on the promise of not dealing with the technology and instead freeing people up to deal with the implementation.  The problem is there’s still some rough spots in clouds and it doesn’t deliver the same experience as on premises.  Of course a slight network drop on some machines from 5 to 6 isn’t a nice experience either.


Oh well, fire up the performance/netmon and see if I can figure out what’s going on.

8 Thoughts on “So I’m fighting an issue at the office that is VERY annoying.

  1. I’ve seen a similar thing before where we found it to be Volume Shadow copies that was the issue.
    It only happened on one server, and we couldn’t figure out why it happened, but turning snapshots off fixed the job.
    It was on a LUN that we weren’t worried about snapshots for, so in the end we didn’t waste too much time on it, and just turned VSS off.
    We found that most apps weren’t quick enough to notice it, but there were some legacy apps, and also offline file sync that were quick enough to notice it every time.

  2. I’ve seen a similar thing before where we found it to be Volume Shadow copies that was the issue.
    It only happened on one server, and we couldn’t figure out why it happened, but turning snapshots off fixed the job.
    It was on a LUN that we weren’t worried about snapshots for, so in the end we didn’t waste too much time on it, and just turned VSS off.
    We found that most apps weren’t quick enough to notice it, but there were some legacy apps, and also offline file sync that were quick enough to notice it every time.

  3. “So the virtual did not drop the connection like that, the real computer did”

    That makes sense. The network packets to/from the virtual machine are delayed just enough so that it doesn’t see the problem.

    Things to try

    1) Make sure your switch/switches have the latest firmware.

    2) Turn off autotuning for the tcp/ip stacks on the machines and server

    3) Check with your NIC card manufacturer to see what size the interframe gap is:

    http://en.wikipedia.org/wiki/Interframe_gap

    http://support.microsoft.com/kb/315237

    4) Swap network cables

    5) Swap network jacks

  4. “So the virtual did not drop the connection like that, the real computer did”

    That makes sense. The network packets to/from the virtual machine are delayed just enough so that it doesn’t see the problem.

    Things to try

    1) Make sure your switch/switches have the latest firmware.

    2) Turn off autotuning for the tcp/ip stacks on the machines and server

    3) Check with your NIC card manufacturer to see what size the interframe gap is:

    http://en.wikipedia.org/wiki/Interframe_gap

    http://support.microsoft.com/kb/315237

    4) Swap network cables

    5) Swap network jacks

  5. I have similar problem with 1 laptop on the network .. everyday between 5-6 PM is loosing conenctivoty and freezes up … I think it has something to do with sync and offline files .. since I have disabled the offline .. seems to be back in normal …. just my 2cents

  6. I just thought of something else ! Do you force all your NIC cards to a fixed speed and duplex or do you use Auto ? I never use auto. If you are using Auto try a fixed speed and duplex. Make sure to set it the same for the switch ports if your switch supports that.

  7. If the server is 2008 and is acting as a domain controller, you might want to try disabling security signatures:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\LanmanServer\Parameters
    Enablesecuritysignature = 0
    Requiresecuritysignature = 0

    We had trouble with Microsoft Access databases. They would hang 10 hours after the user logged on. If you are starting at 7:00 or so, that may fit your situation as well. It only happened on our Windows 7 systems, not on our Windows XP systems. (We don’t have any Vista systems.)

    Microsoft product support recommended we disable security signatures while they investigate further.

  8. We had a similar problem with network dropouts caused by a broadcom nic driver incompatibility with virtual pc & virtual server. It wasn’t as regular as the drops mentioned above, more random until a driver upgrade resolved it.

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