This is not really un upgrade, (although this can be done if the hardware is suitable), but rather setting up a new server, installing ESXi 8.0 and migrating existing VMs to the new box. Note that in this case there is no shared storage, due to geographical issues.
It's probably a good idea to browse some of the notes before setting off.
- SD card/USB boot device revised guidance (85685)
- Eval version of VMvisor 8.0
- Other ways of migrating VMs and here..and here...
- OVF stuff...
- CPU issues
- Step by step of how to install VCSA 8.0
- Use of vim-cmd over SSH
- Once you have installed VCenter 8.0 you then need to update it - which is not simple!
- And if the language of VM<ware confuses you, then try this!
- Another good walk through of ESXi 8
- vSphere Lifecycle Manager Depot.. explained - sort of..
- How to up date the VM h/w level - I can never remember this! Remember this might not gain you anything and might also make your VMs incompatible with Veeam for instance or older ESXi rigs.
And if you need the older 'exe' vSphere clients, this site has a good list of them.