You can join multiple vCenter Server systems using vCenter Linked Mode to allow them to share information. When a server is connected to other vCenter Server systems using Linked Mode, you can connect to that vCenter Server system and view and manage the inventories of the linked vCenter Server systems.
Linked Mode uses Microsoft Active Directory Application Mode (ADAM) to store and synchronize data across multiple vCenter Server systems. ADAM is installed as part of vCenter Server installation. Each ADAM instance stores data from the vCenter Server systems in the group, including information about roles and licenses. This information is replicated across all of the ADAM instances in the connected group to keep them in sync.
When vCenter Server systems are connected in Linked Mode, you can perform the following actions:
Log in simultaneously to vCenter Server systems for which you have valid credentials.
Search the inventories of the vCenter Server systems in the group.
View the inventories of the vCenter Server systems in the group in a single inventory view.
You cannot migrate hosts or virtual machines between vCenter Server systems connected in Linked Mode.
For more information on troubleshooting Linked Mode groups, see the vSphere Troubleshooting documentation.