This is part 2 of a series. Click here to see Part 1. I apologise for taking so long to get Part 2 posted. Sometimes I just don’t have the time or effort I would like to have with the blog.

This portion of the guide focuses on the second half of the VSS to VDS migrations. We needed to move the VMs to a VSS so that you can migrate both VMs and hosts to the new vCenter cleanly. Then we will be moving the VMs back to a VDS from their VSS configuration.

Keep in mind this migration is being done LIVE with production virtual machines running on the hosts. Obviously, this must be executed carefully or you will have a lot of explaining to do. Do not make these changes without understanding the full impact to your environment.

**** PHASE 2 ****

ESXi Host Migration to New vCenter

The following will migrate the hosts from the existing vCenter to the new vCenter server while the VMs continue running. Once all the hosts have been migrated to the new vCenter the VM networking will be moved back the the VDS (Virtual Distributed Switch). We will follow basically the same steps we followed in phase 1, to move back to the VDS from the VSS. Any VMs running on a PvLAN will NOT have network connectivity for the duration of the move until they are re-attached to the VDS (in LEG 2).

LEG 1

1. Individually disconnect each ESXi host from the old vCenter
2. Add each ESXi host to the new vCenter until all hosts are moved
3. Place target host into maintenance mode
4. Remove ONE of the hosts uplinks to vSwitch2
5. Attach what was the vSwitch2 uplink vmnic to the VDS uplink NIC
6. Remove the host from maintenance mode
7. Verify network configuration using testing VM
8. Repeat process for all hosts individually

LEG 2

1. Using the ‘Migrate Virtual Machine Networking’ tool migrate ALL VM networks as required from the VSS to the VDS networks
2. Repeat the Migrate Virtual Machine Network for each VM Port Group until all VMs are migrated
3. At this point all VMs should be running from a VDS
4. Place target host into maintenance mode
5. Remove host from the VDS
6. Add the vmnic that was on the VSS vSwitch2 to the VDS
7. Remove host from maintenance mode
8. Repeat process for all remaining hosts

All VMs should now be running on the VDS. The VDS should have redundant uplinks A + B from all ESXi hosts in the cluster. The migration to the new vCenter is now completed.

Post-Tasks:

• Cleanup (remove) VSS vSwitch2 configuration on ESXi hosts
• Re-enable Cluster HA, DRS, EVC, and Storage DRS
• Move VMs to correct VM Folders, Set Permissions, etc

References / Sources:

• http://kb.vmware.com/kb/2034602
• http://kb.vmware.com/kb/1029498