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There has been a vCenter Server architecture transition for a couple of years. In the past, VMware supported an external Platform Services Controller (PSC) that ran as a separate VM and provided certain vSphere services, such as SSO, license, certificates, or directory services. It was a recommended architecture for multi-site or large-scale deployments.
Luckily, the external Platform Services Controller (PSC) deployment model from versions 6.0 and 6.5 was removed a while ago, so vSphere 7 only uses the embedded model, where the same VM runs the vCenter Server and PSC services on the same virtual machine (VM).
If you are using an external PSC, then the upgrade process now automatically converges the deployment into the embedded model.
vCenter Server converge utility
Make sure to check the VMware Product Interoperability Matrices and the VMware Compatibility Guide for the latest paths.
Before you upgrade or migrate your environment to vSphere 7, you must move any deprecated deployment topology to a supported deployment topology.
Deprecated topologies and vCenter upgrade paths
We can sum the vCenter version and upgrade possibilities into five major points. Please note that some of those versions are no longer supported by VMware.
- vCenter 5.0 or 5.1 with updates cannot be directly upgraded to 6.5; an intermediate upgrade to 5.5 or 6.0 is required. So, if you still have vCenter Server 5, make sure to upgrade it to vCenter 5.5 first.
- vCenter 5.5 or later can be directly upgraded to 6.5 or U1. This one is easy, since from here you can easily upgrade to 6.5, and then 6.7.
- vCenter 5.x cannot be directly upgraded to 6.7; an intermediate upgrade to 6.0 is required (see above.)
- vCenter 6.0 or later can be directly upgraded to 6.7.
- vCenter Server on Windows is no longer available in vSphere 7, so any previous versions must be converted via the assistant. (There is a "Migrate" option when you run the VCSA installer.) Windows vCenter Server must be v5.5 or v6.0 (any build/patch) to migrate to vCenter Server appliance 6.5. If Windows-based vCenter is v5.0 or 5.1, upgrade to 5.5 first and then migrate to VCSA 6.5.
During the upgrade to the latest vCenter Server 7, there is a tool called the vCenter Server Converge Tool, which allows you to migrate the external PSCs into the embedded ones. When executed, the Converge Tool checks whether you'll need any additional components via internet access (if you have one), and those components will be automatically downloaded from the VMware Online Repository.
For topologies with multiple vCenter Servers and the transition to embedded PSCs, VMware has developed a new UI within vCenter Server where selected vCenter Server(s) can be converged to embedded topology.
Converge to embedded
When running this utility, your external PSC will be shut down and unregistered from the single sign-on (SSO) domain.
The embedded PSC doesn't only simplify the vCenter architecture and patching, but you also have fewer VMs to manage and less consumption of RAM, CPU, or storage. If you have large-scale architecture with many PSCs, then the conversion can save a good amount of resources.
Migrating Windows-based vCenter and Windows-based PSC
When running vCenter Server and PSC on Windows as separate VMs, you can migrate an external PSC instance from Windows to the appliance.
It is a two-stage process:
- You'll need to deploy a new vCenter Server to the target ESXi host or a compute resource in the target vCenter Server.
- The second stage completes the vCenter Server setup and copies data from the source vCenter Server for Windows to the deployed vCenter Server.
vCenter Server Migration Assistant
Mount the VCSA installer CD on the Windows VM that you're converting, and run the VMware Migration Assistant on the Windows machine. It's a CLI utility you'll find in a subfolder. Just follow the instructions from the assistant. At the end, you can decommission the external PSC after making sure it is unregistered from SSO. It is important to leave the Migration Assistant window open until you complete the upgrade or the migration process of your vCenter Server deployment.
Note: If anything goes wrong, you should know that you can do a rollback by reverting the source appliance or vCenter Server on Windows. If that's needed, please see VMware KB 2146453.
What can be migrated?
During the Migration Assistant process, you can monitor the migration and manage what you want to bring over with you. The previous version of vCenter might also have had an external database. You have the possibility to migrate the data from the external DB to the embedded PostgreSQL database in vCenter Server 7. You can also migrate vCenter tasks and history. The progress of the migration is shown in the browser window.
Final thoughts
VMware has finally simplified vCenter Server 7. We no longer have to deal with two versions (Windows and VCSA), and we no longer have to deal with external PSCs.
vCenter Server 7 runs on a single VM. But if necessary, we can add more resiliency with vCenter Server HA, where three nodes of vCenter Server instances running at the same time are able to ensure that you don't lose a hand when one instance of your vCenter Server becomes unavailable.
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This topic is a part of a free learning resource allowing you to pass VMware Certification VCP-DCV 2020 based on the vSphere 7 product. The whole study guide, available here VCP7-DCV Study Guide – VCP-DCV 2020 Certification, helps you master all the topics required to become VMware Certified.
