To be able to run and use the Update Manager server and the Update Manager Client plug-in you must ensure that your environment satisfies certain conditions. You also must ensure that the vCenter Server, vSphere Client and Update Manager are of compatible versions.
Before you install Update Manager, you must set up an Oracle or Microsoft SQL Server database. If your deployment is relatively small and contains up to 5 hosts and 50 virtual machines, you can use the bundled SQL Server 2008 R2 Express database, which you can install during the Update Manager installation.
You can install the Update Manager server component on the same computer as vCenter Server or on a different computer. After you install the Update Manager server component, to use Update Manager, you must install the Update Manager Client plug-in and enable it on the vSphere Client.
If your vCenter Server system is a part of a connected group in vCenter Linked Mode, you can install and register Update Manager instances with each vCenter Server system. You cannot use Update Manager for the vCenter Server systems in the vCenter Linked Mode without registering Update Manager instances with them.