Internally within my company, there is usually a lot of discussion about how a customer goes about managing multiple vCenter servers. With the vSphere 5.1 addition of Single Sign-On (SSO), it dramatically complicates the design itself. This topic won't mean much for SMBs because you should be pretty well off with a single vCenter and SSO instance. This is primarily going to be focused on large enterprise designs.
WARNING::: these are MY design considerations and recommendations, use at your own risk. All depicted diagrams do not represent the entirety of a solution. many components are probably missing, so use your imagination.
In the olden days, multiple vCenter environments and geographically dispersed sites could easily be seen in a single vSphere Client view by configuring them in Linked Mode. Linked Mode is great for having fewer panes of management. There are a lot of cons with this route as well:
- A degradation hit in your scalability. (as of vCenter 5.1)
- Maximum of 3000 hosts
- Maximum of 30,000 powered on VMs
- Maximum of 50,000 registered VMs
- Upgrading one site may bring another offline because of build or version incompatibilities
- Time synchronization is critical (but this should usually be critical in any production application)
Now why isn't vCenter Linked Mode a good route for continuing down this path? The addition of 5.1's SSO brings in a critical requirement: Make sure that all vCenter Servers in a Linked Mode group are registered to the same vCenter Single Sign On server. Read more at Linked Mode Prerequisites for vCenter Server
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