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Category Archives: Microsoft Hyper-V

Second network adapter and TCP Offload

I have been having all fun and games trying to get a second NIC to work correctly using Microsoft Hyper V (core and full install). I could see the NIC and configure but the VM would not see the network.

I first thought that Hyper V didn’t like the brand of network card, so I ordered some others. But in the meantime, I have found a solution.

It comes down to an advanced NIC option – TCP Offload. This option is normally on by default on the NIC’s that I have seen. The TCP Offload is an option which was first used way-back-when PC’s were not as powerful as they are now. It would give the CPU a break from digesting network traffic and send it straight to the NIC. In this modern era, we do not need to do this any more. Also, disabling this option is supposed to assist in quicker network transfer speeds – we will see.

So how do you disable it? Open up your network card properties and click on the ADVANCED tab. The screen will look similar to this:

The 3 options that I disable are “IPv4 Checksum Offload”, “TCP Checksum Offload (IPv4)” and “TCP Checksum Offload (IPv6)”. Please note, the screen shot above has lumped in TCP and UDP together – that’s OK. Your network card driver may do a similar thing or separate them. Just disable TCP when you can.

Your VM’s will work like magic now.

 

 
 

Failed to join domain

I was setting up a new Hyper-V Core server with 3 network cards – 2 x LAN and 1 x WAN. I configured all cards with static IP Addresses. But when I attempted to join the domain, I received a very unhelpful error message:

Failed to join domain

And that’s it! No event log, nothing! Great. Now where do I go?

After searching all the corners of the internet, I found a solution. The problem was in the way the Hyper-V box ordered the network cards. It made the WAN card the first in the queue, so of course, when I attempted to connect it to the domain, it was going out into the Internet to find our domain. Doh!

To change the “order” of the network cards, you need to change the “Interface Metric”. In a normal Windows GUI, you can change each NIC interface metric by going into the properties of the NIC’s IP address, choosing advanced, and then manually changing the metric that way. NOTE: lower numbered metrics go first – but don’t choose ‘0’ as this signals an automatic metric which will put you back to where you are now. After you have changed the values, reboot for good measure.

But, if you have a server core machine without a GUI, then you need to perform some command line work.

Open a command prompt and do the following:

To display all of the adapters in the computer with their current IP addresses to determine the correct adapter name, type the following command:

netsh interface ip show config

To change to a static address, type the following command:

netsh interface ip set address “Local Area Connection” static ipaddr subnetmask gateway metric

For example, I need to change my Local Area Connection #7 to a metric of 5, I would do this:

netsh interface ip set address “Local Area Connection 7” static 172.16.1.10 255.255.0.0 172.16.1.1 5

And after a reboot, you will be able to join your server / PC to the domain without a problem.

 

Error (2916) VMM is unable to complete the request. The connection to the agent was lost.

This error message appeared when I built a new HyperV 2008 R2 server and a System Center Virtual Machine Manager server when I attempt to convert a physical server to a VM:

Error (2916) VMM is unable to complete the request. The connection to the agent <server name> was lost.

The easiest way to correct this error is to perform the following on the HyperV server:

  1. In the open command prompt, type the following: winrm quickconfig
  2. When prompted, enter Y for the default answer

You should now be able to add your physical server.

 
 

The virtual machine could not be started because the hypervisor is not running

My quest to try out Microsoft Hyper-V R2 2008 is on going. I decided to install my first Hyper-V virtual machine. But, of course, it was not that easy.

This lovely box appeared:

Hyper-V requires hardware support, including: an x64 CPU; VT (Intel) or AMD-V (AMD) hardware extensions; No eXecute (NX)/eXecute Disable (XD) and full BIOS support for hardware virtualization.

The problem is that in your computer BIOS, the virtualization option is not enabled. By default, virtualization in the BIOS is disabled.

Your CPU needs to be able to support virtualization. Check the specs on your CPU.

To enable this, restart your computer and enter the BIOS. Every system board differs so just read the on screen instructions on how to enter the BIOS (normally DEL or F10).

Once in the BIOS, navigate to CPU settings or advanced settings (may be called something else depending on your BIOS). Look for anything related to virtualization and enable it.

Save the settings and TURN OFF your computer. This will allow the BIOS to enable the feature on start up.

NOTE: Be very careful in the BIOS. If you change the wrong setting, your PC may not boot or become unstable.

Source: http://social.technet.microsoft.com/wiki/contents/articles/194.aspx

 
 

Copy files to Hyper-V Server

I have a stand-alone Hyper-V 2008 R2 server and I needed to copy ISO files over to it. After a short search, I proceeded with the following commands on the Hyper-V box:

netsh advfirewall firewall set portopening ALL 139 “Share1″

netsh advfirewall firewall set portopening ALL 445 “Share2”

After a reboot of the Hyper-V server, I could browse to the C: drive of the server, create a folder and copied across the ISO files needed to create the new servers. Yay!

 
1 Comment

Posted by on April 10, 2012 in Microsoft Hyper-V, Virtualization

 

Cannot connect to the RPC service on computer . Make sure your RPC service is running.

I was getting really frustrated with this problem when I was trying to connect a Windows 7 PC to my Microsoft Hyper-V 2008 R2 server. No matter how many posts I read, nothing would work. Until one post made me think to double check my IP address settings on my Hyper-V box.

Low and behold my subnet mask was incorrect. Once that was changed to the correct setting, all was fine in the virtual world.