How to create an ESXi usb installer on Mac OS X

A couple of days ago I wanted to test VMware ESXi 5.5 on a Mac Pro 4,1 (quad-core XEON 2.66GHz / 8GB RAM).  I had a couple of issues doing this, mostly my fault as, of course, I jumped straight in and didn’t read any of the documentations.  Anyway, once I had read the documentation there were still a few things not covered, so I thought I would document the steps I took to get the platform installed:

  • First Off you have to get the installer files from the vmware site – the UK portal is – you’ll have to make an account on the site but no billing information is needed, and it only takes a couple of minutes, so it’s all good.  The installer files are packaged in a .iso files and the whole image is about 400MB.
  • Get your USB key – as the source files are so small a 512MB or 1GB key is sufficient.
  • Next, format the USB key with a Master Boot record partition map and a FAT32 file system.  Although you can do this through Terminal (man diskutil to find out more), the quickest way is to use Disk Utility:
  • Next, open Terminal, located in the /Applications/Utilities folder.
  • In Terminal, type in ‘diskutil list’ and hit enter to see all of the volumes mounted on your system.  Find the system designated name for the USB key – You will know which disk it is by looking at the sizes of all of the volumes and the volume name.  In my case the USB key is called ‘ESXI’ and has the designation ‘/dev/disk2’, as you can see in the image below:
diskutil list - mac repairs london

Find the system designated name for the USB key, double check by verifying volume name and size.

  • We’ll now have to use the fdisk command to flag the USB key’s partition as bootable, but to do that you’ll have to first unmount the USB key from the system.  In Terminal type ‘diskutil unmount /dev/DISKNUMBER’ (as above).  If the command works you’ll get a Terminal confirmation that the volume has been unmounted.
  • Next, enter fdisk’s interactive mode and select the desired volume – you can do this with ‘fdisk -e /dev/disk2’
  • At the fdisk interactive prompt  type ‘f 1’ to flag the first partition on the volume as active and bootable.  Follow these commands with ‘write’ and next ‘quit’ to leave fdisk.  If at any point you get an error, make sure the volume has been unmounted but not ejected.  You can always use the unmount button in Disk Utility.  After this is complete, remount the USB key onto the Desktop.
  • Close Terminal and mount the ESXI installer .iso.  Copy all files from the installer onto the USB Key – you can use Terminal to do this but I simply dragged and dropped through the Finder.
  • The last step is to modify a file on the USB key to tell the system which partition to use when booting up – on the USB key find the file called ‘ISOLINUX.CFG’, rename it ‘SYSLINUX.CFG’ and open it in any Terminal text editor such as vi or pico or open it in TextEdit (but do not open it in MS Word!).
  • In the document, find the line that starts ‘APPEND -c boot.cfg’ and add ‘-p 1’ on the end (without the quotes).  Save and Close TextEdit.
  • Now, if all things have been done correctly and successfully you should have a bootable ESXi USB Key! The disk won’t show up as bootable in System Preferences -> Startup Disk but it will work.




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'How to create an ESXi usb installer on Mac OS X' have 20 comments

  1. 31/12/2013 @ 2:52 am Matt

    Thanks for the tip.

    Any chance you’ve tried to get ESXi 5.5 running on a Mac Pro 1,1 (first gen.) machine? I currently run version 5.1 on a 1,1 MP and it works great. I’ve been thinking about upgrading but remembered all of the stuff I had to do to get it to work (using a modified bootloader/kernel because the machine lacks full 64 bit boot).

    I’m guessing doing an in-place upgrade to 5.5 would break it on that machine so I’m really too afraid to try and I haven’t seen anyone mention running it on this vintage of box.



    • 16/01/2014 @ 11:24 pm James Spong

      Hi Matt,

      I’ve heard it can work but I haven’t actually tried it. It isn’t supported by VMWare though so if there are any problems, you’ll be on your own and things like patches/bug fixes etc. won’t be applicable to your installation.

      I have a Mac Pro 1,1 in the office – I’ve been meaning to test install esxi 5.5 on it – When I get round to it, and if it works, I’ll write up my experiences here, so check back here every now and then and it’ll hopefully be up.



  2. 16/01/2014 @ 8:21 pm Henry

    Thanks James this worked like a charm, I have been having problems getting this to work for a couple of hours until I came up this.


    • 16/01/2014 @ 11:26 pm James Spong

      No problem – thanks for commenting!


    • 27/08/2015 @ 5:29 pm djflynnuk

      Just want to add my thanks, also having problems until I came across your page.


  3. 02/05/2014 @ 1:48 pm SteveE

    I’m planning on doing this.
    Is the MacBook Pro OSx operating system still available for normal use after doing this?
    I’m hoping that this procedure is not destructive?!


    • 02/07/2014 @ 8:56 am James Spong

      Hi Steve – No, it’s completely fine and won’t damage anything – at least, I have neither damaged anything myself or heard of anyone damaging their own computers. First check with ESXi to see if the MacBook Pro is supported or it may not work/act strangely. I have a feeling the MBPs aren’t supported and that it’s only the Mac Pros.


  4. 22/11/2014 @ 1:54 pm MrVining

    Great guide!
    One note, shouldn’t it be ” -p 1″ rather than “-p 1” for selecting the right partition?


    • 08/02/2015 @ 3:12 pm James Spong

      Hi – yes, I guess so. I think at the time of writing I added a space after the first ” to signify that there should be a space after the last character on that line. In hindsight, maybe it wasn’t needed :p


  5. 26/01/2015 @ 4:07 am Bootable USB for installing stuff – creating bootable USB installer from OS X | IP Communications

    […] I did this coz there was an old server that didn’t have the DVD drive and I wanted to install ESXi. Follow here: […]


  6. 03/02/2015 @ 9:25 pm Robert

    I followed these instructions to the letter and they did not work :-/


    • 08/02/2015 @ 3:14 pm James Spong

      Hi, I just tested this again on a 10.9.5 Mac Pro and it worked fine – where did it go wrong – in Terminal or on boot? There are a few updated commands for Terminal on later Macs. I’ll probably do another post about it as this seems to get quite a lot of traffic. Let me know anyway…


      • 21/02/2015 @ 5:25 pm James

        MacOS The Disk ‘Version 13 (517) on OS X 10.9’ has no option to partition as ‘FAT32’, only options were FAT, ExFAT, and MacOS Extended so I created 1 partition MS-DOS (FAT), type Master Boot Record.

        When I tried out the process, the USB disk did not become bootable. System boot process went through all devices and ended with “Reboot and Select proper boot device or Insert Boot Media in selected Boot device and press a key”

        The fdisk command does throw up an error.

        $ sudo fdisk -e /dev/disk2
        fdisk: could not open MBR file /usr/standalone/i386/boot0: No such file or directory
        Enter ‘help’ for information
        fdisk: 1> f 1
        Partition 1 marked active.
        fdisk:*1> write
        Writing MBR at offset 0.
        fdisk: 1> quit


  7. 26/02/2015 @ 12:18 am Sajith Kumar

    Not sure where I went wrong. Except the below error everything else went as expected..

    MacBook:~ root# fdisk -e /dev/disk1
    fdisk: could not open MBR file /usr/standalone/i386/boot0: No such file or directory
    Enter ‘help’ for information
    fdisk: 1> f 1
    Partition 1 marked active.
    fdisk:*1> w
    Writing MBR at offset 0.
    fdisk: 1> q

    But the USB disk is not booting at all. Any suggestions


  8. 11/10/2015 @ 3:01 am John Todd

    Just ran this on ESXI 6.0 and it runs fine on a 2,1 Mac. Thanks for the tips! Well-written.


  9. 16/12/2015 @ 5:35 pm Robert Juric

    You are my hero!! I’ve been fighting trying to get my esxi .iso onto a bootable usb all day and this finally cleared it up. I think the magic that I was missing was the fdisk command to make the partition active.


  10. 24/12/2015 @ 10:52 pm DJ

    I also have not been able to get this to work, but I suspect that is because I am trying to get the USB drive bootable from a system with UEFI instead of BIOS. Do you know how to make it actually boot on a Mac Pro? It looks like the EFI boot stuff should be there, but I could not even get it to work by burning a CD image of the ISO.


  11. 22/02/2016 @ 10:33 am Syed

    Nice Blog appreciate your efforts to contribute it work as a charm to me.


  12. 23/02/2016 @ 2:46 am Ian

    Has anybody tried this with OS X 10.11 (El Capitan)? I mark the partition as bootable (f 1) and it puts an * next to it but the * goes away when I “write”.


    • 23/02/2016 @ 2:50 am Ian

      More specifically, going into fdisk seems to be the issue:

      ian$ sudo fdisk -e /dev/disk3
      fdisk: could not open MBR file /usr/standalone/i386/boot0: No such file or directory
      Enter ‘help’ for information
      fdisk: 1>


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