VMware started to move away from Windows dependency, as they call it, a few years back. VMware now has its own Linux distribution called Photon OS. VMware vCenter Server Appliance (VCSA) is a preconfigured virtual appliance built on Project Photon OS. VMware developed the OS, and it benefits from enhanced performance and faster boot times compared with the previous Linux-based appliance.

The product has a built-in database called vPostgres, which is based on the well-known PostgreSQL database. This means VMware has full control of the whole software stack, which allows them to optimize the VCSA for vSphere environments.

Also, security plays a big role nowadays, and owning the software stack allows for a much quicker release of security patches. The VCSA scales up to 2,000 hosts and 35,000 virtual machines (VMs), and the feature set of the VCSA is now greater than the vCenter Server installed on Windows.

Why migrate from Windows to the Linux-based vCenter?

To put it plainly, VMware is phasing out the Windows version of vCenter. It's as simple as that. Previous years were pretty tough for VMware as the VCSA wasn't scalable, did not provide the full feature set, and was not optimized. Now the VCSA 6.7 Update 1 (U1) has more features than the Windows-based vCenter.

vCenter requirements:

  • Make sure your third-party products (such as backup and monitoring) are fully compatible with the version of vSphere you are upgrading to. If not, you won't be able to back up your VMs, for example.
  • The Windows vCenter Server must be v6.0 or v6.5 (any build or patch).
  • It doesn't matter whether your current vCenter is a VM or is running on a physical server. Both physical and virtual vCenter Server installations are compatible.
  • You can migrate any database, internal or external, supported by vCenter Server to VCSA (it copies the data from the old database to vPostgres).

ESXi requirement:

vCenter Server 6.7 U1 should be running ESXi 6.0 or above.

Note: If you have still hosts with ESXi 5.5 and earlier versions, you must upgrade them to ESXi 6.0 first.

How does the upgrade process work?

During the upgrade process, there are several phases:

Phase 1 (clean deployment of the VCSA): This phase deploys the VCSA with a temporary IP address, copies the data from the old vCenter, and then powers off the Windows server.

Phase 2: Once the VCSA is online, you choose what to copy and what you need to migrate from the Windows server. The process will inform you when it successfully completes the data transfer and the VCSA is ready for use.

The migration outline

Go and connect to your old Windows-based vCenter Server with sufficient privileges. Mount the VCSA 6.7 U1 installation ISO, copy the migration-assistant folder to your desktop, and then unmount the ISO file.

Open the folder and r

Copy the migration assistant folder

Copy the migration assistant folder

un the VMware-Migration-Assistant.exe as an administrator. It opens a command prompt window and asks you for a single sign-on (SSO) password.

Enter the password and hit Enter.

It then does several checks, and at the end it posts a message, "Waiting for migration to start…"

Waiting for the migration to start

Waiting for the migration to start

If all checks succeed, the Migration Assistant finishes its execution and waits for the migration.

You can now leave the system and go to your management workstation from which you'll perform the migration. You can use Windows, Mac, or Linux.

Mount the VMware VCSA 6.7 U1 installation ISO on your management workstation or laptop.

Mount the VCSA 6.7 installation ISO

Mount the VCSA 6.7 installation ISO

Then execute the installer.

Execute the VCSA Installer

Execute the VCSA Installer

From the main screen, click the big Migrate button, which allows you to migrate from a Windows platform to the VCSA.

Choose Migrate from Windows

Choose Migrate from Windows

The assistant will start providing you with the different migration steps, which are easy to follow. We won't list them all here, just the principal ones.

The screen below shows the details about the source connection. You'll need to provide the IP address or fully qualified domain name (FQDN) of the source system and credentials for the SSO.

Connect to the vCenter source on Windows

Connect to the vCenter source on Windows

You'll get a certificate prompt, which you can accept.

Next, you'll need to specify the appliance deployment target. This is basically the ESXi system that will execute the VCSA VM. It can be standalone ESXi or ESXi managed by vCenter Server.

Appliance deployment target

Appliance deployment target

Next, you'll be setting up some details about the VCSA VM, such as its name and location within your data center. Then you'll go to Select deployment size where you can choose the Deployment size and Storage size.

Select deployment size

Select deployment size

Following this, you'll select the datastore to use for the location of the VM's files (the location of the virtual disks).

After this, you'll just need to fill in the network settings, including a temporary IP address for the appliance. Once the migration and copy process finishes, the source system shuts down, and the installer will automatically assign the original IP address of the old vCenter Server to the new VCSA. This is pretty cool because you don't have to reconfigure anything.

Configure network settings

Configure network settings

Click Finish to start the process. The first phase (Stage 1) will deploy the appliance.

You'll need to specify some additional parameters between phase 1 and phase 2. Mainly, the process will ask you whether you want to keep the old historical data and so forth.

Select what you want to migrate

Select what you want to migrate

Then the second phase (Stage 2) will copy the database details, statistics, alarms, network settings, and historical data.

Make sure you have a backup of your old Windows vCenter VM (click the checkbox).

Ready to migrate

Ready to migrate

As you can see, the process is pretty straightforward, and VMware has documented it well. Anybody can do it.

Stage 2 of the migration

Stage 2 of the migration

Well, this is pretty much it. When the migration finishes, you have the option either to Launch vSphere Client (HTML5) or Launch vSphere Web Client (based on Adobe Flash).

Choose your web client

Choose your web client

The whole upgrade process can easily take one hour or longer.

You can now proceed with upgrading your hosts, as the migration (and upgrade at the same time) of vCenter was just the first step.


Migrating ESXi is pretty easy, and you can choose different migration methods. You can migrate ESXi via ISO or CD-ROM, and you can also do it via USB flash device or via network.

At the enterprise level, for migrating many ESXi hosts en masse, you'd probably look at the vSphere Update Manager (VUM) component, which is now also part of the VCSA and provides an easy way to migrate ESXi hosts from earlier versions.

  1. Avatar
    Geniek 5 years ago


    when specifying appliance deployment target can I point it to the same vCenter server being migrated? As we use distributed switches and probably when connecting directly to ESXi host those will be not visible?

  2. Avatar Author

    The vSphere 6.7 documentation:

    “You can connect to a vCenter Server instance and browse the inventory to select an ESXi host or DRS cluster on which to deploy the target appliance.”

  3. Avatar
    Geniek 5 years ago

    Hi Vladan,

    yes I saw this document. But it is not mentioned if it can be the same vCenter server I plan to migrate. As this vCenter will not be available all the time during migration process. I suppose it can be but need to be sure.

  4. Avatar Author

    It is available during the deployment phase and copy phase. It’s only stopped at the end, after everything is copied and the new VCSA inherits the networking details, vCenter IDs, etc….

    So I think the old vCenter will be available like 99% of the time.

  5. Avatar
    shivaraj 4 years ago

    Hi, We are facing an issue while upgrading 6.0 U3d to 6.7. The issue is " Encountered an Internal error. See /var/log/firstboot/vpostgres-firstboot.py_****_stderr.log". Please let me know if anyone faced the same issue and is there any resolution for this.

  6. Avatar Author


    You should check VMware Product Interoperability Matrices. It seems that you can't upgrade directly from 6.0U3 to 6.7. 


  7. Avatar
    Peter 3 years ago


    I’m trying to upgrade the Windows based vCenter 6.5 to VCSA 6.7 on the ESXi 6.5. Running migration-assistant.exe, when the prompt asks for the password of the SSO account Administrator@vspheer.local. I typed in the password. Then I get the prompt stated that vCenter service is running with the local account and I need to type in the password for that local account. I typed in. The migration-assistant run check, return with the error stated that the local account does not have privilege to perform the migration. My setup is that the Windows server used for vCenter is not on the domain, but Windows Workgroup. The local account run the vCenter service has full administrator right on the Windows and on vCenter. I’m stuck. Is there any way that I can specify the Administrator@vsphere.local to run as a service for vCenter? Or any other suggestion to resolve the issue? Thanks in advance for your help/suggestion regard this matter.

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