Migrating VMs running on VSS to VDS in a Production ESX cluster (Migrate Virtual Machine Networking…)

With one of our ESXi 5.0 clusters growing to 12 hosts and our Networking team constantly wanting to deploy new vlans like they are going out of fashion it was time to implement a distributed vSwitch (vDS) to the cluster in order to reduce the administrative overhead of adding all of the port groups to each vSwitch on each host (not really the case but it’s always good to keep up with the professional dogging of those poor network guys eh?). 

The process to deploy a new vDS to a cluster is pretty straight forward and you can follow the process from within vCenter here: VMware KB

Once created the next step was to create each of the vlan port groups onto the VDS.  Here I simply setup the vlan with the same name as used currently on each of the VSS (you can do this as the name has ‘(dvswitch)’ appended to it anyway so it keeps these separate from the existing port groups when selecting network connectivity when editing VMs) and the same vlan ID entry etc.

Next I moved 2 of the 4 x 1Gb adaptors from each VSS into the dvuplink ports on the VDS.  This then allowed the existing VSS port groups to continue to service network requests for all of the running VMs and also allowed me to start moving VMs from the VSS to VDS .

To migrate the VMs from their current port groups on each VSS to the newly created port groups on the VDS you can use the excellent Migrate Virtual Machine Networking utility which manages the bulk modifications to VMs.

To do this simply so to the networking screen in the VI client and right click on the new VDS and choose ‘Migrate Virtual Machine Networking…’

Next select the source network from the drop down list (this is the current port group that you want to move VMs off of) and then select the destination network (the corresponding port group on the dvSwitch)

Click Next and you can now select all or some of the VMs to be migrated.  If you select all of the VMs you’ll be able to sit back and watch as each VM is modified in turn and moved over.  It really is simple and best of all results in no network outage to the running VMs.

I migrated several hundred VMs across our various vlans to the distributed switch without one little blip! 

Then it was a just a matter of going through each of the hosts and cleaning up the old port groups and vSwitches which were no longer being used.