ELM - Enhanced Linked Mode Setup Question

[Roger Haines]

I'm attempting to setup ELM for an existing vCSA environment consisting of 4 vCenters.  

Question #1:  Is it possible/ supported to do this on vCSA's/ vCenter servers that are already built and in production?  

Question #2:  Is there a hierarchy that needs to be considered?  In other words, is one of the vCenters considered the "Primary/ Master"?

Anyone care to share their experience with setting this up?  Pros / Cons?  Etc?

Best Regards,

RH

[svaghani1]

When setting up Enhanced Linked Mode (ELM) for an existing vCenter Server Appliance (vCSA) environment, it is indeed possible to do this with vCenters that are already built and in production. ELM allows you to link multiple vCenter Server systems so you can manage them from a single platform, sharing various configurations such as roles, permissions, and licenses across all linked Instances.

1. Setup in Existing Environment: Enhanced Linked Mode can be configured on vCenter Servers that are already deployed. You can create an ELM group during the deployment of vCenter Server Appliances or it can be configured post-deployment. However, the deployment of a new component like a Platform Services Controller (PSC) as part of the ELM setup needs careful planning. It's important that you review the latest VMware compatibility matrices and documentation for any prerequisites or exceptions.

2. Hierarchy and Primary/Secondary Roles: In an ELM setup, there isn't a strict "primary/master" hierarchy among the vCenter Servers. The concept of 'Primary' or 'Secondary' relates more to Platform Services Controllers (PSCs) when discussing replication topologies rather than the vCenters themselves. Each vCenter server joins a Single Sign-On (SSO) domain, allowing them to share identities and attributes without designating a clear primary vCenter within the ELM.

3. Pros and Cons of ELM:

   • Pros: Central management, unified visibility across linked vCenter Servers, and consistent policy enforcement across sites.
   • Cons: Complex troubleshooting and backup considerations, especially in relation to ELM replication. As highlighted in support experiences, restoring backups might require VMware Support assistance to address replication discrepancies.

I got this from Tiyaro DeepQuery so please help yourself if you want detailed steps or references

[Roger Haines]

Thank you for your response and particularly the explanation of hierarch/ Primary & Secondary roles.

[pcgeek2009]

We had a similar configuration a few years ago before moving to VCF. Ironically, we also had 4 vCenters in ELM. Most of the time it was great. We had all locations in one login, and you could easily move between environments. However, one major downside was certificates. There was one particular instance where the certificate expired on the primary and the only way we were able to get everything working again was with a support ticket. As previously mentioned, troubleshooting can become complicated. There were several times support, depending on the issue, wanted all 4 vCenters shutdown and clean snapshots taken before they started making changes. This way, they were all 4 at the same point in time in case there were any issues. We later decided against ELM when we moved to VCF due to some of these issues. We really do most of the work in one environment and occasionally do some in the smaller ones. 

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Rodney Barnhardt
vExpertPro
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[Roger Haines]

Hi Rodney,  Great feedback.  Thank you!  Does VCF give you a "single pane" type of experience with managing multiple vCenters?  One of our primary drivers for ELM is use a shared content library for ease of managing host profiles and templates.  Any thoughts?