Server 2012r2 to server 2016 Hypervisor Upgrade - SCVMM - Logical Switches

  • 3 October 2018
  • 2 replies

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Hi, I'm hoping someone may be able to help here, we are in the process of planning a Hypervisor upgrade from 2012r2 to 2016 on Dell XC servers.

The article here

states "Logical networks might not be restored immediately after upgrade. If logical switches are configured, the configuration will not be retained and VMs might become unavailable."

We are using logical switches and I don't want to lose VM connectivity, however there is no advice on guidance on what to do in this scenario.

My question is our Hyper-V hosts have logical switches configured, therefore on the host itself my switch has a different name that is no longer the nutanix default "ExternalSwitch" and is called "LogicalSwitch" for example

If we used the one-click method and the host is rebuilt with Server 2016, what happens here is the "LogicalSwitch" retained on the host or is the host configured with the default "ExternalSwitch"

I have logged these queries with support and I am not particularly confident with the responses I have got. Has anyone done this with logical switches configured or can advise in this scenario please.

2 replies

curious to know if anybody has an answer for this. i'm also looking at doing an upgrade on a hyper-v installation, also with logical switches.
Badge +4
curious to know if anybody has an answer for this. i'm also looking at doing an upgrade on a hyper-v installation, also with logical switches.
I don't have the answer, but I have a workaround.

So I was still not happy that I had two conflicting answers, one where support said all network configuration "should" be retained but then the documentation states "logical switches will not be retained"

I simply could not risk seeing what happens on a production cluster.
So I queried regards doing this manually one node at a time, and this is what I did, it is possible but time consuming
  1. CVM Shutdown
  2. Maintenance mode in VMM
  3. Remove node from cluster in VMM
  4. Remove node from VMM
  5. Install Win Server 2016, create 2.0GB partition on disk
  6. Boot from Phoenix
  7. Run firstboot script
  8. Change Computername
  9. Configure networking
  10. Add to domain
  11. Add to SCVMM
  12. Assign logical switches to host
  13. Change CVM to use logical switch in HV manager
  14. Add to failover cluster through SCVMM
  15. Test VM migration
One important caveat that I was not informed of when doing this, the newly converted host will still be a member of a Server 2012r2 cluster (version 5.0), the CVM is created at version 8.0 this means the CVM will start on the host outside of the cluster, as soon as the host is a member of the cluster if you attempt to reboot the CVM it will not start !!! As the cluster will not allow version 8.0 machines, in order to remedy this situation the host must be removed from the cluster then the VM can start. Then of course you can add it back in again. Support forgot to tell me this bit as well. So it is important to upgrade all the hosts within a relatively quick timescale then you can upgrade the cluster functional level to 8.0.

I would not attempt this without consulting support first, but it does work as I've done it.
I note as well on 5.10 release notes "Ensure that non-default vSwitches are preserved during upgrade to Windows Server 2016 Hyper-V." so it may even be possible now !