This document is about upgrading vSphere 5.1 to 5.1 Update 1.
Phase 1: Preparation
You need these listed below:
Phase 2: Upgrading vCenter and additions
Phase 3: Upgrading ESXi
Phase 4: VMtool upgrading
Upgrade VMtool on each virtual machine.
Phase 5: vSphere Client upgrading
Upgrade vSphere Client on all installed computer.
Phase 6: Troubleshooting
If there are some templates in your vSphere, you may need to convert them to virtual machine to upgrading VMtool. If this function is grayed out, you can remove the related template from inventory and add them back.