In my earlier tip on configuring vCenter Linked Mode, I didn’t mention how the configuration maximums are affected when the federation feature is used. When Linked Mode is used, a few categories of the vCenter Server Maximums are changed.
There are four primary categories impacted by the use of Linked Mode vCenter Server systems. The first is that there is a maximum of 10 Linked vCenter Systems permitted. vCenter Server scales very well, so it would be an incredible infrastructure to roll in 10 different vCenter Server systems. This number can be met quicker if the vCenter environments are smaller due to separation by chargeback, development vs. production, or other business functions. There also can be a maximum of 1,000 hosts in Linked Mode, which is not 10 times the standalone vCenter Server limit. The singular vCenter Server has a maximum of 300 hosts running a 64-bit operating system. The other limits related to Linked Mode are powered-on virtual machines (10,000) and registered virtual machines (15,000). The primary situation where these limits can be reached for many environments is a VMware View VDI environment.
The configuration maximums document does not address a limit for roles and permission models that may be set across vCenter Server systems. With the vCenter Server permissions model, administrators can craft creative roles that are applied to vCenter Server systems. The one caution I would make, as in any permissions model, is to follow Active Directory best practices and not create too many nested levels of permission.
The vCenter Configuration Maximums document is one of the most useful documents, and is a critical tool for the VMware certification path. Be sure to check out the vCenter Server section of the configuration maximums document for all Linked Mode related changes.