Before you upgrade an ESXi host:
A.
Save the ESXi configuration using vicfg-cfgbackup s from the vCLI
B.
Update the ESXi restore CD with the current ESXi image
C.
Save the current ESXi image to another ESXi server
D.
Copy the embedded ESXi image to a USB flash drive
Explanation:
vSphere Upgrade Guide ESX 4.0 ESXi 4.0 vCenter Server 4.0 vSphere Client 4.0 , page 71.Back up the host configuration before you begin a host upgrade. For more information about the VMware vSphere Command-Line Interface and the vicfg-cfgbackup command, see the vSphere Command-Line Interface Installation and Reference Guide.