The upgrade of VirtualCenter 2.0 to 2.5 is the first step of upgrading VMware Virtual Infrasctructure 3.0x to 3.5. In this article I'll describe the steps I took to upgrade VirtualCenter.

The upgrade is not hard and you don't have any downtime. You can do it during office hours, even if you have lots of VM's running and customers depend on them. Isn't this grand!

The plan was simple but effective:
Create a new VM and install VC 2.5, after just having stopped the VMware service on the VC 2.0 server. I used a copy of my production database so I had a solid roll-back scenario.

The upgrade of the Oracle 10 database took about 30 minutes. The database was 8 months old and contained data of 4 ESX servers containing around 60 VM's.

After the succesfull upgrade of the database I had some issues connecting the ESX hosts to the VirtualCenter:
error: "unable to access the specified host"
The vmware-vpxa service on the ESX host should be automatically replaced during the connection process, this did not work. Solution:
Log in as root on the ESX:
# service vmware-vpxa stop
# service mgmt-vmware restart

From your VC try a "connect" again, this should work.

I still had a problem with one ESX that did not want to connect.
error: "connection problem"
Solution: restart your VC client. A bit tricky I'd say, because you think you maybe have to reboot the ESX while I had VM's running on this one. But I'm very happy this was not necessary.

After connecting all of my ESX hosts the HA cluster was still not working. I had to rebuild the HA cluster. Just disable it on the cluter object and enable it again. I think I could have done this as the first step.

I hstill had to upgrade the VIrtualCenter software on my physical VC server. So I stopped the VMware service that connects to the database on the virtual VirtualCenter server. I uninstalled the VC2.0 software on my original physical VirtualCenter server and installed the VC 2.5 software. Now I connected the ESX hosts to the VirtualCenter 2.5 on the physical host.

Voila. How more easy can upgrades of these very important company wide used computer systems get?