You can install, upgrade, or migrate ESXi from a CD/DVD drive using a script that specifies the installation or upgrade options.

About this task

You can start the installation or upgrade script by entering a boot option when you start the host. You can also create an installer ISO image that includes the installation script. With an installer ISO image, you can perform a scripted, unattended installation when you boot the resulting installer ISO image. See Create an Installer ISO Image with a Custom Installation or Upgrade Script.


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.


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


  1. Boot the ESXi installer from the CD or DVD using the local CD/DVD-ROM 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.