Automated ESXi 6.7 U2 Zero Touch Install via USB

Almost zero-touch, after you create a file

Image credit: Unsplash

Having a homelab shouldn’t revolve around installing ESXi, it should be about what you do on top of it.

In fact, installing ESXi should be painless, automated, and trivial.

I’ll cover how to create a bootable USB that will install ESXi unattended. The USB will auto-install onto itself; making it the boot disk afterwards.

Unlike a local disk or SAN LUN, USB/SD devices are sensitive to excessive amounts of I/O as they tend to wear over time. This naturally raises a concern about the life span of the USB/SD device. When booting from USB/SD keep in mind that once ESXi is loaded, it runs from memory and there is very little ongoing I/O to the boot device. The only reoccurring I/O is when the host configuration is routinely saved to the USB/SD device, which by default is done once every 10 minutes. Based on how often you reboot the host and install patches it is expected that a good quality USB should last for several years. source

This is a repeatable process for fearless homelab ESXi installs while preserving any existing local VMFSs. If previous VMFSs exist, you can always clean them up after ESXi is running for a fresh slate.

Table of Contents


  • ESXi server
  • USB drive (reliability is more important than size over 1GB)
  • Linux PC (like Ubuntu) with USB port

The USB that you use to provision ESXi will install the OS on itself. Meaning, after you prep the USB stick and plug it in, it will become your ESXi boot disk. Forever.

This can be modified in the ks_cust.cfg at your own risk.

Get VMware ISOs

You can download a free 30 day trial of ESXi. However, I’ll be using my EVALExperience. For $180, EVALExperience provides 1 year of VMware licenses for personal use.

Using EVALExperience to download ISOs

There’s a detailed walkthrough at After signing up for EVALExperience proceed.

  • Login to
  • Find VMware vCloud Suite Standard 7
  • Click Add To Cart and Checkout
  • Save the 2 keys that are provided:
VMware vCloud Suite Standard 7 (English) - Download
  • Download ISOs for ESXi and vCenter
    • VMware-VMvisor-Installer-6.7.0.update02-13006603.x86_64.iso
    • VMware-VCSA-all-6.7.0-13010631.iso

Create a bootable USB

I’m using a Sandisk 8GB USB 3.0 drive, but any similar drive should work.

You need a USB port for formatting the drive. I suggest NOT using a VM to avoid USB passthrough problems.

Identify the USB disk path

fdisk -l

This step may require root (sudo su -)

It helps to double check the size from another source for comparison. Accuracy is crucial!


As you can see above, I will use /dev/sda as MY USB location, please validate YOUR USB location.

Make sure the USB device is unmounted.

umount /dev/sda # ignore if not mounted

Create a partition table

fdisk /dev/sda
  1. Type d to delete partitions until they are all deleted.

  2. Type n to create primary partition p.

    • Set default 1 that extends over the entire disk.
    • Take default sector ranges too.
  3. Type t to set the type to an appropriate setting for the FAT32 file system c.

  4. Type p to print the partition table.

     Disk /dev/sda: 7.5 GiB, 8004304896 bytes, 15633408 sectors
     Units: sectors of 1 * 512 = 512 bytes
     Sector size (logical/physical): 512 bytes / 512 bytes
     I/O size (minimum/optimal): 512 bytes / 512 bytes
     Disklabel type: dos
     Disk identifier: 0xb2521ac2
     Device     Boot Start      End  Sectors  Size Id Type
     /dev/sda1        2048 15633407 15631360  7.5G  c W95 FAT32 (LBA)
  5. Type w to write the partition table and quit.

Format the USB (FAT32)

/sbin/mkfs.vfat -F 32 -n USB /dev/sda1

If you have issues, make sure the partition and volume are unmounted (umount /dev/sda && unmount /dev/sda1)

Install the SYSLINUX bootloader

SYSLINUX is a suite of lightweight master boot record boot loaders. We’ll use it to prep the ESXi USB.

The locations of the syslinux executable file and the mbr.bin file might vary. If you are running Ubuntu, you most likely have it already.

Check if you have the syslinux executable

which syslinux

# expected: /usr/bin/syslinux

Check if you have the mbr.bin file by running the following one-liner.

[ -e "/usr/lib/syslinux/mbr/mbr.bin" ] && echo "file is present" || echo "file does not exist"

# expected: file is present

If above conditions are met, proceed.

syslinux /dev/sda1   
cat /usr/lib/syslinux/mbr/mbr.bin > /dev/sda

Mount the USB

mkdir /usbdisk
mount /dev/sda1 /usbdisk

Mount the ESXi ISO

mkdir /esxi_cdrom
mount -o loop VMware-VMvisor-Installer-6.7.0.update02-13006603.x86_64.iso /esxi_cdrom

Make sure to replace the ISO with the proper version (above).

Copy the ISO contents to the USB

cp -r /esxi_cdrom/* /usbdisk

Customize SYSLINUX

Rename isolinux.cfg to syslinux.cfg.

mv /usbdisk/isolinux.cfg /usbdisk/syslinux.cfg

In the syslinux.cfg file, edit the APPEND -c boot.cfg line to APPEND -c boot.cfg -p 1.

nano /usbdisk/syslinux.cfg

Create a ks_cust.cfg script

Start with my personal template and edit to taste.

curl -L -o ks_cust.cfg
nano ks_cust.cfg

Alternately, copy / edit and paste this template to ks_cust.cfg in your working directory.

For more ideas of what’s possible, see VMware’s documentation.

Copy ks_cust.cfg to the USB

cp ks_cust.cfg /usbdisk

Update boot.cfg

In the boot.cfg file, edit the kernelopt=runweasel line to kernelopt=ks=usb:/ks_cust.cfg.

nano /usbdisk/efi/boot/boot.cfg

After you’re complete, unmount the flash drive umount /usbdisk and the ISO umount /esxi_cdrom.

Boot the ESXi host

Insert the USB stick in the powered down ESXi server and turn it on. You may need to configure your BIOS to boot from USB (or select it from a menu).

Once the USB drive loads, you will see it auto-configuring ESXi.

Durring the install, it is ok for the server to reboot 1 or 2 times.

Validating install

  • Find IP of ESXi host either via GUI or other methods.
  • Navigate to and login using root and your password set earlier (r00tp@ssw0rd).


At this point you can modify the ks scripts even further. You could also create duplicate copied USB sticks for multiple hosts.

Jim Angel
Jim Angel
Everything Computers & Cloud

I’m an Infrastructure Cloud Consultant at Google. I love demystifying Kubernetes and related concepts. Part of my journey includes serving as a documentation co-chair for Kubernetes.

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