Upgrading the operating system on which vCenter server is installed is something that can be done without the need of creating a new database, and it can also be done in a couple of different ways. In order to upgrade the Windows operating system you should follow Microsoft’s recommendations, but when doing an in-place upgrade all services related to vCenter should be stopped before proceeding.
vCenter Server Services

Another approach to this upgrade would be to simply install vCenter Server in a newly provision system with the current and desired version of Windows. Now in order to do this effectively perform the following steps before installing vCenter Server:
- Stop vCenter related services in the Windows Services snap-in (services.msc) of the running server
- Create a new System DSN pointing the new server to the database location
- Import the SSL keys from the running server