WARNING – This is not VMware’s supported method to move hosts on vDS between vCenters. I don’t recommend you do this in production environments. See comments on the post below for more information. Also see my list of known concerns at the bottom.
This post describes a method to migrate ESXi hosts configured with the vSphere Distributed Switch (vDS) to a new vCenter directly, eliminating the need for intermediary standard switches (vSS). This article focuses on networking, other aspects of the migration are discussed elsewhere. This can be done with running workload (VMs) on the ESXi hosts.
In this scenario, the customer’s goal is to take existing ESXi 5.5 hosts, currently managed by vCenter 5.5, and bring them under management by vCenter 6. The process cannot cause an outage or downtime.
I’m working within a couple of established constraints: First, we previously decided the migration path will be to stand up new vCenter 6 instances (using the awesome new VCSA) and then to disconnect/reconnect hosts to the new vCenters. Second, I’ll be working with production VMs running on the ESXi hosts, and I do not want to cause any interruption of service.
Also, consider these two important factors regarding the ESXi host configuration:
- All port groups and management ports are assigned to a vSphere Distributed Switch
- Storage is native Fibre Channel exclusively, and won’t be impacted by this migration.
Here’s the method:
- Export the current Distributed Switch configuration – use the Web Client and see https://kb.vmware.com/kb/2034602
This will create a .zip file that contains your current Distributed Switch configuration.
- In the new vCenter, import the Distributed Switch configuration. Ensure you check the box for “Preserve original distributed switch and port group identifiers“
By selecting this checkbox, the new vCenter can recognize the port groups and virtual switch specified in the migrated ESXi host local configuration.
Consider what features you may want to temporarily disable for the migration, such as HA and DRS.
- Disconnect the ESXi host(s) from the current vCenter (right click on the host, choose Disconnect). Running VMs continue to run.
- Add the ESXi host(s) to the new vCenter 6 environment
Now we are going to add the new hosts to the new distributed switch, so that vCenter recognizes the hosts as attached to the switch. This will require minimal configuration.
- Right-click the new Distributed Switch and choose “Add and Manage Hosts”
- Select the “Add Hosts” task
- On the next screen, select all of the newly migrated hosts
- On the “Select network adapter tasks” screen, select only the first option, “Manage physical adapters”
- For the remainder of the wizard, keep the defaults. Just click Next and Finish until you are done.
- Wait… a few minutes.
After several minutes, the distributed switch “Related Objects” tab will show the migrated virtual machines and ports that are connected.
Caveat – as always, test before running any unknown or new process in your production environment.
Hope this helps.
UPDATE 4/5/16: Here’s a list of issues that other folks have identified with this. Let me know if there are any others for consideration.
- The managed object IDs are likely to be different in the new vCenter. If you have any scripts or tools that directly reference objects by ID, the current references will be invalid in the new environment.
- The UUIDs are preserved (by design). If you intend to keep the source vCenter active, you now have two vCenters with objects with duplicate UUIDs.
- New OVA deployments are known to fail (not confirmed for vSphere 6)
- (Update 1/11/17) – Also, some internal IDs may become out of sync vs. normal expected behavior, which can have unintended / unanticipated consequences.