To *use* Enhanced VMXNET or *not* -- that's my question

[geekinabox]

My company is executing on an upgrade to VI 3.5. We're at about 120 hosts and 1800 VMs (comign from 3.0.2).

As we evaluate new features in 3.5 we've come across Enhanced VMXNET.

We understand what this is, but are trying to decide what to do with it. Is this a feature worth implementing? And if so, how? Assuming your hardware and guest OS support it, is it worthy of implementation on all guests? Or are there only certain segments of guests that woudl benefit from this? In other words, should we consider this as the default for all of our VMs, or should we only do selective application?

Are there any potential drawbacks from overusing it? Ie., is there a reasonable chance that TSO could be overwhelmed if all of our VMs used it?

With our current 1800+ guest environment (and growing) it will be difficult to assess on a manage on a VM-by-VM basis (without a clear, measurable critieria)

Also: currenlty none of our hosts are connected to network segments that use jumbo frames, so I don't think that that is a relevant critera for us, for now.

thanks for any input.

[Lightbulb]

You best starting out with the default adapter for your guest VM. Over time you may find the need to change the adpater to enhanced to meet a particular challenge (We have had issues with particular apps and configurations that were resolved by the switch) for simplicity sake given the size of your environment it will be easiest to go with the default and only switch if needed.

I do not know of any issues of over deployment of VMs with enhanced adapter capability having an impact on the physical network architecture.

Jumbo frames are not officially supported with ESX as of yet (although i gather you can trick around that) as you say though not really your worry at this time.

[kjb007]

I use the enhanced vmxnet NIC for all my vm's. If for nothing else, then consistency, as all of the vm's I currently run can use the enhanced NIC, as opposed to the flexible/e1000. I've run into what appears to be a bug, at least for now, but it comes about using the vi toolkit to manage the NIC settings.

Other than that, the NIC runs fine. Keep in mind though that the driver only runs with the tools, so if you lose the vmware tools service, you lose your NIC connectivity. If you run a lot of Linux vm's, and keep up-to-date with kernel patches, then this may not be the best option. Every kernel update would require you to manually rerun the config script for the tools service to get your networking back up. Not very efficient, and there may be a better way coming soon, but for now, rebooting after a kernel update means no NIC. You'll have to then use the console on every vm to rerun the config script. We've worked around the issue by using a script that checks for kernel updates, and if the kernel has been updated, then the config script is run after boot, and the server is rebooted again, and voila.

-KjB

VMware vExpert

[RParker]

As we evaluate new features in 3.5 we've come across Enhanced VMXNET.

Yes, it's worth it. However, the enhanced version doesn't seem to work. I got it to work on Windows XP 64-bit, once. I tried with Windows 2003 (32-bit and 64-bit) didn't seem to make a difference. I installed in Redhat and Suse, neither would get an IP address (fresh installs).

And I recently tried again with Windows 2008. Same problem, it wouldn't connect or get an IP. I finally decided it wasn't worth my time, but theoretically it would make things better, and hopefully your experience will be better. But I wanted to experiment myself, and it was just too much hassle.

So I say go for it, but make sure you test thoroughly before moving on to other machines. Especially the network performance, you may find it doesn't seem to 'enhance' anything.

[thomps01]

It might be worth giving it another stab since 3.5 update 4 was released yesterday and specifically addresses the OS versions you mentioned with Enhanced vmxnet

Expanded Support for Enhanced vmxnet Adapter - This version of ESX Server includes an updated version of the VMXNET driver (VMXNET enhanced) for the following guest operating systems:

• Microsoft Windows Server 2003, Standard Edition (32-bit)

• Microsoft Windows Server 2003, Standard Edition (64-bit)

• Microsoft Windows Server 2003, Web Edition

• Microsoft Windows Small Business Server 2003

• Microsoft Windows XP Professional (32-bit)

[RParker]

It might be worth giving it another stab since 3.5 update 4 was released yesterday

I will take that into consideration. But between having spent countless hours, many configuration changes, and doing testing with the VM's that I did manage to get to work, it didnt' seem worth the trouble. And I am usually the quickest and the first to test new versions of ESX, but since this new update doesn't hold anything compelling, and with vSphere just around the perverbial corner, I am not all that enthralled with having to update an ESX server and change some stuff around JUST to find out it doesn't work. That's not thrilling at all.

So unless I see someone else that says that it's worth the trip, I am not ready to pack my bags. That's why I am encouraging the poster . . . .;)

[msemon1]

I had the same problem with 2 Windows 2008 /Exchange 2007 servers. It could not get an IP so I just changed it back to e1000. Is this a bug or "feature'

Mike

[kjb007]

Make sure tools are running correctly. As I stated above, the tools are integral here, unlike the flexbile NIC previously. I use it on my RHEL/win2k3/win2k8 x86/x64 vm's.

-KjB

VMware vExpert

[Texiwill]

Hello,

Moved to Virtual Machine and Guest OS forum.

I use vmxnet for everything unless I suspect vmxnet is causing a problem then I test with the pcnet32 or e1000 drivers.

Best regards,
Edward L. Haletky
VMware Communities User Moderator, VMware vExpert 2009
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Author of the book 'VMWare ESX Server in the Enterprise: Planning and Securing Virtualization Servers', Copyright 2008 Pearson Education.
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