You can install, upgrade, or migrate ESXi from a USB flash drive using a script that specifies the installation or upgrade options.

About this task


After you upgrade or migrate your host from ESX/ESXi 4.x to ESXi 5.x, you cannot roll back to your version 4.x ESX or ESXi software. Back up your host before you perform an upgrade or migration, so that, if the upgrade or migration fails, you can restore your 4.x host.

Supported boot options are listed in Boot Options.


Before running the scripted installation, upgrade, or migration, verify that the following prerequisites are met:


  1. Boot the ESXi installer from the USB flash drive.
  2. When the ESXi installer window appears, press Shift+O to edit boot options.

    ESXi Installer screen

  3. 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=.

  4. Press Enter.


The installation, upgrade, or migration runs, using the options that you specified.