A short guide on creating bootable USB media for ESXi.

Requirements – Highlights the requirements for creating and installing the media

Method 1: RUFUS Installation – How to use a single USB key as both the installation and target media

Method 2: Setup a virtual machine – Setting up the environment to pre-Install ESXi to a machine to allow you to simply plug and play in your server.

ESXi Installation – Installation process for ESXi


Minimum ESXi Requirement
Memory 4GB
Processors 2
Processor Technologies Intel VT-x/EPT or AMD-V/RVI

Minimum flash drive size: 4Gb

Note: a high quality USB device is required at this size due to no free flash cells being available for redundancy.

Recommended: 16Gb

A full list of requirements can be found in the vSphere 5.x Documentation Center

I would recommend using Method 1: RUFUS Installation to perform the installation if you do not have access to/would prefer not to use a client with an optical drive.

Method 1: RUFUS Installation

Thanks to electricanimal and liquus on Reddit for the suggested method.

There is an awesome Utility called RUFUS you can use to create USB install media.

Furthermore you can then use the same USB to intall ESXi to, removing the need for any additional software/equipment.

If however you want to pre-install ESXi to enable a simply USB swap and reduce downtime on the server please follow Method 2 below.

The below tutorial is done using RUFUS 1.4.12

  1. Download RUFUS from here:
  2. Since RUFUS is a standalone portable exe simply extract to a folder of your choice and double click to run RUFUS.exe
  3. RUFUS Utility
    RUFUS will now detect any plugged in USB storage devices
  4. Select target USB
    > Click the drop down box under Device
    Select your target usb device
  5. Select the ESXi install image
    > Click the CD-Rom icon beside Create bootable disk image using ISO image
    > Browse to ESXi Installation media
    > Click Open
  6. Build USB
    > Click Start
  7. Replace menu.c32?
    > Click Yes
    This will download a small file to the directory the Rufus.exe is located in
    > Click Ok
    A hidden partition will be created that is not visible in windows, this means windows will not see the USB drive at full capacity until this hidden partition is deleted.
  10. USB Creation will now begin
  11. When the installation is complete you will be returned to the utility
    > Click Close

You are now ready to boot the USB in your target server. Simply follow the instructions below in the section titled ESXi Installation.

Method 2: Set up a virtual machine

This guide is based on VMWare Workstation 8.x, you will need to use a hypervisor with the above minimum requirements to perform a successful install.

  1. Launch VMWare Workstation
  2. Create a new Virtual Machine
    > Click File > New Virtual Machine
  3. Welcome to New Virtual Machine Wizard
    > Check Typical (recommended)
    > Click Next
  4. Guest Operating System Installation
    > Check Installer disc image file (iso)
    > Click Browse
    > Browse to your VMWare ESXi installation media
    > Click Next
  5. Name the Virtual Machine
    > Virtual machine name: VMware ESXi 5.x
    > Location: <your vm store>
    > Click Next
  6. Specify Disk Capacity
    > Check Store virtual disk as a single file
    The vDisk will not actually be needed, however by storing it as a single file it makes it easier to delete should you want to.
    > Click Next
  7. Ready to Create Virtual Machine
    > Click Customize Hardware
    > Click the Memory configuration option
    > Memory for this virtual machine: 4096 MB (4GB)
    > Click the Processors configuration option
    > Number of processors: 2
    > Check Virualize Intel VT-x/EPT or AMD-V/RVI
    > Click Close
    > Click Finish
  8. Add USB/SD Card reader to device
    > When the VM starts up move the cursor by pressing up/down arrow keys to stop timer
    > Plug in your USB device or SD Card
    > Click VM
    > Click Removable Devices
    > Click the USB Device or SD Card reader
    > Click Connect (Disconnect from host)
  9. Optional: For ease of installation remove the local hard disk
    > Click VM
    > Click Settings
    > Click the vDisk
    > Click Remove
    > Click Ok
Note: There is currently an issue with Windows 10 build 9860 to 9926 (the current latest) and shutting down VMWare Workstation causing the host OS to crash.
A workaround for this issue can be found here:

ESXi Installation

From this point forward the procedure is the same regardless whether you are performing the installation using a virtual machine or a physical host.

  1. ESXi Boot Menu
    > Select ESXi-5.x.x-<build date>-standard Installer
    > Press Enter
  2. Welcome Screen
    > Press Enter
  3. End User License Agreement
    > Press F11
  4. Select a Disk to Install or Upgrade
    > Highlight your USB Device/SD Card
    > Press Enter

    Note: If at this point you have forgotten to plug in your USB Device/SD Card
    Insert the device now and press F5 after a few seconds.However if you have plugged in the device and it is not detected it may be inconpatible with ESXi, check the vSphere Compatibility Matrix for further information.
  5. Please select a keyboard layout
    > Highlight your preferred keyboard layout (in this case United Kingdom)
    > Press Enter
  6. Enter a root password
    > Enter your preferred password
    > Press Enter
  7. Confirm Install
    > Press F11
  8. Installation will now begin
  9. Installation complete
  10. If you are using a USB/SD Card that is less than 8 Gb do not boot the device at this point. Please refer to the following guidance
    When installing ESXi onto a USB flash drive or SD flash card, if the drive is less that 8GB is space, this prevents the allocation of a scratch partition onto the flash device. VMware recommends using a retail purchased USB flash drive of 16GB or larger so that the “extra” flash cells can prolong the life of the boot media but high quality parts of 4GB or larger are sufficient to hold the extended coredump partition.
    To workaround this limitation:

    1. Connect to the ESXi host via SSH. For more information, see Using Tech Support Mode in ESXi 4.1 and ESXi 5.x (1017910).
    2. Backup the existing boot.cfg file (located in /bootbank/) with the following command:
      cp /bootbank/boot.cfg /bootbank/boot.bkp
    3. Open the boot.cfg file using VI editor. For more information, see Editing files on an ESX host using vi or nano (1020302).
    4. Modify the following line:
      kernelopt=autoPartition=TRUE skipPartitioningSsds=TRUE autoPartitionCreateUSBCoreDumpPartition=TRUE
    5. Save and close the boot.cfg file.
    6. Restart the ESXi host.

And there you have it, now simply plug in the device to your target server and set the USB/SD Card as the first boot device.

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