What would be the easiest way to migrate a ESXi 4.1 or 5.1 host from an USB stick to a local disk storage device?
Would a fresh installation be necessary?
Before running the scripted installation, upgrade, or migration, verify that the following prerequisites are met:
The system that you are installing, upgrading, or migrating to ESXi meets the hardware requirements for the installation or upgrade. See ESXi Hardware Requirements.
You have the ESXi installer ISO on a bootable USB flash drive. See Format a USB Flash Drive to Boot the ESXi Installation or Upgrade.
The default installation or upgrade script (ks.cfg) or a custom installation or upgrade script is accessible to the system. See About Installation and Upgrade Scripts.
You have selected a boot option to run the scripted installation, upgrade, or migration. See Enter Boot Options to Start an Installation or Upgrade Script.
Boot the ESXi installer from the USB flash drive.
When the ESXi installer window appears, press Shift+O to edit boot options.
Type a boot option that calls the default installation or upgrade script or an installation or upgrade script file that you created.
The boot option has the form ks=.
The installation, upgrade, or migration runs, using the options that you specified.
You can check this documentation to get all the info you need . and i suggest using the USB method as its the easiest ( imo )
VMware vSphere 5.1