Its a very quick process to update ESXi version to the latest. This procedure is completed via esxcli going through a SSH session to the Server. The update takes around 5-10mins depending on the hardware resources of the server and the failure is minimal. But not to say that the things wont go wrong so please make a BACKUP before you proceed.
To start with you first need to download the latest ESXi patch from VMware website. You need have an account with VMware to download the patches.
Once downloaded copy over the patch to the ESXi host via SSH (you can use WinSCP on a windows machine).
Before proceeding with the patch process its recommended to put the host in maintenance mode. There will be a downtime involved for VM's residing on the host. So either you can turn them off or vMotion them to another host.
Now SSH to the ESXi host and run this command with the absolute path of the patch.
# esxcli software vib install -d "/patch/of/the/patch"
esxcli software vib install -d "/vmfs/volumes/535ed7a3-aa9364ec-54b9-001fc68da6c5/Esxi-update/update-from-esxi6.0-6.0_update02.zip"
Once you run this command you need to wait 5-10mins and then you should see a similar screen as below as to whether its successfull or not. If successfull, you need to reboot the host.
Once the host is rebooted you should be able to see the updated ESXi version as given in below screenshots.
Before the update
After the update
Once the updated version is verified you can now go ahead and exit the maintenance mode.
That's it all done and if any issues please let us know via Contact Us and we will be delighted to help.