Windows 7 NIC Detection Issue / Script to Remove then Add the NIC Back


One of my customers has been having an intermittent issue with their Windows 7 VDI Desktops.  Occasionally after they update the Operating System, when the desktops boot back up they fail to use their NICs.  The NIC is still attached to the VM and is still on the right network, but Windows fails to recognize it (it doesn’t get a DHCP address and, in fact, registers within the OS as being physically disconnected from the network).  Restarting the desktop doesn’t help, reinstalling drivers doesn’t help (we’re using the VMXNET3 network adapter, for those who are interested).  Removing the adapter from Windows seems to be the key to getting the desktop back online.  We’ve gotten desktops back online by removing the adapter from Device Manager and then scanning for hardware changes (and rebooting).  We’ve also removed the NIC from the VM (with the VM shut down) and replaced it; that’s also alleviated the issue.

Unfortunately, those steps just alleviate the symptom.  They get people back up into a working state, but I’ve got no idea what’s actually causing Windows to freak out over its NIC.  Does anyone have any ideas?  Since removing the NIC and adding a new one resolved it, I originally thought that it was related to the specific device (maybe Windows ties something to the MAC address and gets messed up, preventing that card from coming online again), but the problem is alleviated simply by removing the NIC from Device Manager, which allows the same NIC to be rediscovered and function.  That led me to believe that it might be a driver issue, but reinstalling my NIC driver didn’t resolve the issue (and, removing/restoring the NIC doesn’t actually reinstall the drivers)… so now I’m not sure where to look for a solution.

To make life easier, I wrote a quick PowerCLI Script that goes through that process for a list of VMs (you’ll have to provide that list in the array at the start of the script).  The script is super basic, it just identifies the NIC in the current desktop, removes that NIC, Adds a new VMXNET3 NIC to the same network that the original NIC was on, then powers on the VM.  The Script will only run on VMs that aren’t running, so make sure you shut down your desktops before you try this.  As always, this is provided as is with no guarantees and is only for educational purposes.  Also, beware of unintentional line breaks due to the width of the blog.



$OfflineDesktops = @("Desktop1", “Desktop2”, “Desktop3”)
foreach ($VM in $OfflineDesktops){
                $nic = Get-NetworkAdapter -VM $VM
                Remove-NetworkAdapter -NetworkAdapter $nic -Confirm:$false
                New-NetworkAdapter -VM $VM -NetworkName $nic.NetworkName -Type vmxnet3 -StartConnected
                Start-VM -VM $VM
}
Update: I found a reference that sounds suspiciously like this issue at  http://support.microsoft.com/kb/2526142.  Now that I have a hotfix to try, I've been unable to reliably recreate the issue!  I'll post an update if I get to the point where I can reliably provoke this failure and if this hotfix resolves it.

Comments

Post a Comment

Sorry guys, I've been getting a lot of spam recently, so I've had to turn on comment moderation. I'll do my best to moderate them swiftly after they're submitted,

Popular posts from this blog

Clone a Standard vSwitch from one ESXi Host to Another

One of my customers is standardizing the configurations on their HP C7000 enclosures (they've been set up at various sites by various administrators with varying involvement from the architecture team).  As such, we need to stand up some temporary resources so that we can take down the main enclosure for reconfiguration.  That's fine, we can easily ship a smaller enclosure to each site for temporary compute resources.  Some of the sites are using Standard vSwitches, so we need to be able to quickly copy the networking configuration over from their existing blades to these new, slightly different blades.  As I see it, we had 2 good options: 1) Capture a Host Profile with the desired vSwitch configuration.  Delete every other component of the Host Profile so that only the networking section is applied; design the new ESXi hosts so that the vSwitches'll work with the old vmnic-to-vswitch configurations. 2) Write a script to clone the vSwitch from ones ESXi host...
Read more

PowerShell Sorting by Multiple Columns

PowerShell's Sort-Object cmdlet is super useful, especially when preparing output for human consumption.  A few people have found my blog while looking for more information about its use, specifically while looking for how to sort by multiple columns (well, properties, technically).  I've never done so (much less written about it), so I hope those folks found answers elsewhere.  But, it got me curious... and it turns out that it's really easy. The Technet article on Sort-Object has the answer directly spelled out: just use commas to create a list of properties to sort by (in order to precedence).  Let's look at some examples!  First, prepare a variable with some good sortable data: $myData = get-eventlog System -newest 25 And then we can get to sorting!  Say you want to sort primarily by EntryType (Warning, Information, Error) and then by Source.  Easy-peasy: $myData | sort EntryType,Source How about if you want it to be in descending or...
Read more

Deleting Orphaned (AKA Zombie) VMDK Files

A problem that most Virtualization Administrators need to deal with is Orphaned VMDK files (or Zombie VMDK files, as some people call them).  These are Virtual Machine hard drive files that are just hanging out, taking up storage, but are attached to no VMs.  How can this happen?  Well, the most common way is when an administrator needs to delete a VMDK but isn't quite ready to commit... so, after pressing "remove", they select "remove from virtual machine" rather than "remove and delete files".  The intent is always good: "I want to be able to restore this if it turns out to be necessary... so I'll just come back and delete it next week if nothing breaks!"  But, of course, next week something else happens and the file doesn't get deleted.  After a little while, it turns into "which files did I rename, again?" and nothing seems to happen. So, how do you deal with these orphaned files?  Well, a few years ago I found a scrip...
Read more