Here is the super fast version for experienced ESX admin’s…
- Upgrade vCenter 1st (Make sure you’re not using SQL Express, if you are upgrade to SQL Server and update your ODBC)
- Update VMWare Update Manager and run it (Installer is on the VIM CD)
- Use Update manager to import the ESXi5 ISO for a host upgrade baseline (download from vmware.com)
- Put some hosts in Maintenance mode for the upgrade
- Verify all ESX4 hosts have all network connections linked, there is a bug in the upgrade which will stop the process if a NIC is unplugged, even if the team/bond is working.
- Attach the baseline with ESXi5 to them, remediate to upgrade it, careful if you use 3w-9xxx raid since those drivers aren’t native anymore
- After all the hosts are upgraded you can upgrade to VMFS5 with a 0 downtime in place upgrade, VMFS3 is compatible with ESXi5 so you can do this later if you need to
- As VM’s reboot VMWare tools will be updated. Or you can manually update them.
- Here are instruction on updating VM’s from v7 to v8. ESXi5 is backwards compatible with v7 VM’s so you can do this when you need to. It requires VM reboots.