Traffic flow when cold migrating a vm

[roland_geiser]

Hello

Is this statement correct: "When I am cold migrating a (powered off) vm from one ESXi's local storage to another ESXi's local storage via vCenter, the traffic flow goes through the management-traffic-portgroup, not the vmotion-portgroup?"

It's because when I do a hot migrate, regardless of its a vmotion or a vmotion with storage vmotion, then the traffic flow goes through the vmotion port group. It's the behavior that I expect. But why does the traffic not flow through the vmotion-portgroup as well when I do a cold migration? Or ist there a misconfiguration? But I have different port groups on different nic's and there are different subnets configured...and every port group has just one traffic type assigned.

I am just studying: What if I have a 10GB vmotion network and a 1 GB management network? When doing a cold migration, the traffic will choose the slow 1-GB-connection? Everybody is giving as much bandwidth as possible for vmotion, but in that scenario the traffic goes through the management network? I know - in most cases we are doing a vmotion or svmotion. But I was astonished when I detected, that the traffic choses the management port group and not the vmotion port group...

Is this really the default behavior as described?

Best regards

Roland

[weinstein5 · Accepted solution]

Yes that is correct - with cold migration the data does move across the management network and this is the espected behavior -Traffic does not through the vMotion network because a Cold Migration is not vMotion - also depending on whether your shared storage supports VMware Storage APIs or not will depend on whether the data stays on your storage network or onto you public network.

Also 10 GB in my opinion is overkill for your vmotion network - it is designed to work with 1 GB -

[roland_geiser]

Thanks for your answer.

10GB for vmotion is really very fast. If you have an ESXi with 256 GB RAM, it's impressive how fast the vms are moved to another ESXi host.

I am testing a configuration with only 2 NICs with 10GB each at the moment and I built it as proposed here: vSphere networking configuration with 10 GbE | VMwaremine - Mine of knowledge about virtualization (szenario one).

I think this design makes sense and I have plenty of speed with vmotion, management and all the trunk ports. (vDS are not available because I don't have enterprise plus licenses)

Best regards

Roland