How To Install VMware vSphere ESX 4 From USB Flash Drive

In case the server  has no DVD/optial drive or  you have an iso but no DVD-r available. 

It is possible to install ESX 4 using a USB flash drive.

1.  Use a bootloader application such as  Unetbootin to create a bootable flash drive using the iso (simply point to the iso file, specify the USB flash drive and click ok) .

2.  Boot the server from the USB flash drive

3.  Click Tab when the ESX install options appear

4.  Add the command askmedia  to the  end of the  syslinux bootloader string  that appears.

The ESX4 installation process will continue as normal, however an additional option of selecting a media path such as USB, FTP and NFS will be available.