VMware Officially released eBook to do upgrade to vSphere 6.5 . There are three phases of the upgrade to ensure a successful process overall whether you are upgrading from vSphere 5.5 or vSphere 6.0. To understand what steps should be taken to support and meet the needs of your organization You can Download and Refer the eBook From below Link.
Also there are many reference links available from the eBook and it is very useful to Administrate the VMware Infrastructure .
Document Contain Below Topics
Also you Can Go to VMware Web Site and and Download the Document