Hi,
I have a Windows VCenter Server 5.5 installed, and plan to upgrade this to U2. Is there any guidance on how to do this exactly?
Thanks
Check this one:
http://www.vmwarearena.com/2013/10/vsphere-55-upgrade-part-1-understanding.html
Take a look at this VMware KB article: VMware KB: Methods of upgrading to vCenter Server 5.5
Basically, you will need just run the installer and choose between using the Simple Install method or the Custom Install that will upgrade the components separately, one at time... I personally prefer the custom method.
Of course, before start the upgrade, remember to make backup of your vCenter (including database) or take a snapshot of vCenter if running on VM.