ELM with different vCenter versions?

[MatthewFB]

Hello Experts,

Working through some possible solutions and looking for clarification on something as I am not finding a specific answer in docs on the vmware site and would save me some time building out a lab to test.

2 vCenters

• 6,5 Update 2 - site 1 - Embedded PSC
• 6.7 Update 3 - site 2 - Embedded PSC

Can Enhanced Link Mode run with 2 different versions of vCenter or must they both be on the same build (6.5 or 6.7)

If so, can I point the vCenter 6.5U2 to the vCenter 6.7U3 embedded PSC controller and enabled ELM to then do vMotions to the new 6.7 from the 6.5?

[daphnissov · Accepted solution]

No, ELM requires homogeneous versions across the board.

[MatthewFB]

Thank you @daphnissov

So with that, what would be the best method for doing migrations from 6.5 to 6.7 both on prem, with minimal downtime, or non at all where possible? Unfortunately our hardware is not officially supported on 6.7 so we want to exhaust all other options first before considering a need to run vCenter 6.7 against hardware not in an RCM. I have looked at the JRE plugin Cross vCenter Workload Migration Utility, possibility to use Hybrid linked mode maybe using the Cloud web gateway but that may only allow connectivity to AWS?

[daphnissov]

You'll have to state what your objectives are here because it's not clear. If you're on 6.5 with hardware that doesn't support 6.7, you can still upgrade vCenter to 6.7 and continue to manage those 6.5 hosts. Otherwise, if your hosts must get up to 6.7, you'll have to migrate those VMs to new hosts. That can be done with the Fling you mentioned and source and destination vCenters need not be at the same version. Please check out the second link in my signature for more info.

[MatthewFB]

Thank you for the reply

The issues is that the infrastructure the current VM's sit on, at the software level they have, are not officially supported under vCenter 6.7 under an RCM. We would need to update the entire UCS systems (firmware/bios et cetera) for all of the equipment which could take several weeks, time we do not wish to spend on something that will be decommissioned. There are concerns of "what if.." an issue does arise under 6.7 if the hardware is not updated with the latest and greatest firmware/bios. So with that, we have a vCenter 6.5 managing that infrastructure. Our new infra, is on VxRail, and we require vCenter 6.7 to manage that.

The question is the most efficient and reliable way to migrate the VM's from the old to the new really with out having to put extensive work into the old UCS systems. ELM was an initial idea but you need same versions. HLM is something I am reviewing as one Amazon Dev noted you should be able to use the Cloud Gateway appliance on prem? using this is what has allowed Amazon to migrate clients into their infra with varying vCenter versions that do not match up to Amazon.

Reviewing your link now.

[daphnissov]

You might be under some false impressions of the purpose of ELM. Enhanced Linked Mode is only for "single pane of glass" management abilities and it has (almost) nothing to do with being able to migrate VMs across those vCenters. For example, you still have to have vMotion connectivity, and you still have to have the same segments presented to both source and destination sites. That's something ELM doesn't check or have any hand in validating (much less performing) for you. So if your only objective is to migrate VMs from a 6.5 vSphere environment over to a "new" vSphere environment on VxRail running vSphere 6.7, you don't need ELM for that. If you read my book, I illustrate how to do this with the Cross vCenter Workload Migration Utility which has no reliance upon ELM. You could perform these migrations with PowerCLI as well and as long as the requirements are met, you shouldn't have any issues.