vSphere Virtual Center Linked Mode Prerequisites:

Well, yes this article has two headers or titles. Guess what they are almost identical.

I have seen “Error 28039. Setup cannot join vCenter Server to the linked mode group” all over the net & without any one posting resolution for it. hmmmm, how did I find out about this error and what made me looking for resolutions, well I had faced this same ugly error in my own lab. The resolution for it was nothing more than following the pre-requisite to vSphere Virtual Center Linked Mode which most people ignore. Below is the pre-requisite that you must follow for a successful installation of vCenter Linked mode & I will highligh the mostly missed one.
All the requirements for standalone vCenter Server systems apply to Linked Mode systems. In addition, to the following requirements:

The following requirements apply to each vCenter Server system that is a member of a Linked Mode group:

  1. DNS must be operational for Linked Mode replication to work.
  2. The vCenter Server instances in a Linked Mode group can be in different domains if the domains have a two-way trust relationship. Each domain must trust the other domains on which vCenter Server instances are installed.
  3. When adding a vCenter Server instance to a Linked Mode group, the installer must be run by a domain
    user who is an administrator on both the machine where vCenter Server is installed and the target machine of the Linked Mode group.  <== This one is what most people miss. What you really have to do in this step is to create a domain service account & add it to the local administrator group of your original virtual center & your new linked virtual center machines. Then login with this account to the new machine to be installed with linked vCenter & when asked for the service account make sure you chose to use the new created service account credintial instead of the default local admin account.
  4. All vCenter Server instances must have network time synchronization. The vCenter Server installer
    validates that the machine clocks are not more than 5 minutes apart.

If you satisfy all of the above requirements specially the DNS one & the service account one(marked in red) you should have a nice successful installation.

Good luck with your installation, and hope to hear some good comments of success story below.