Rufus takes seconds to create a bootable USB flash drive for ESXi installation

Posted by Paul Braren on Sep 10 2013 (updated on Jun 12 2015) in
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  • Mar 12 2015 11:15am EDT update – with ESXi 6.0 now released, worth noting that Rufus still works just fine, including the new but very similar Rufus 2.0 Portable, and this USB flash drive. 8 people are reading this article right now!

    Download Rufus, straight from the author at rufus.akeo.ie, or from reboot.pro:

    The executable is digitally signed and the signature should state:
    "Akeo Consulting" (v1.3.0 or later)
    "Pete Batard - Open Source Developer" (v1.2.0 or earlier)
    Rufus: Reliable USB Formatting Utility (with Source), read the introductionFAQ, and support forum.

    There are many Windows utilities out there that'll help you create a bootable flash drive from your ISO image, normally used for creating CDs or DVDs.

    This article is only focused on quickly and easily making a flash drive boot the ESXi installer, so you can then install ESXi onto this same flash drive. Cool, eh?

    See also Rufus lets you quickly and easily reformat an ESXi USB flash drive back to full capacity TinkerTry.com Sep 10 2013, and the very popular article, Use ESXi-Customizer GUI to inject multiple driver VIBs into your ESXi installer ISO TinkerTry.com Dec 16 2013, works great for ASMedia (SATA), Realtek (NIC), and LSI (RAID).

    There are many methods I've used to create bootable media for ESXi over the last decade or so. All had some drawbacks, including the need to pay very close attention to command line diskpart commands. I was seeking something quicker and easier, and I've settled on Rufus recently, which has the following advantages:

    • free
    • simple GUI
    • can be run from an EXE that doesn't require any installation
    • doesn't require careful attention to command line partitioning commands that can be a bit dangerous
    • much faster than other methods, takes under a minute to follow my instructions below
    • seems to work, every time, back on Windows XP, right through Windows 8

    For folks used to installing Windows or Linux on hard or solid state drives, it may come as a surprise that there's little reason to install your hypervisor there. Why? Well, wear isn't really the issue (explained below). It can be very handy in a lab to be able to shutdown the server, then simply remove and replace the USB flash drive with different USB drive with a different hypervisor. Say, for beta testing. Or testing different VIBs. This swapping allows you to leave all the internal hard drives as-is, datastores for VMs. This is geared toward the home lab enthusiast. In datacenters, the various server vendors often has specific recommendations for certain USB flash devices.

    As long as you boot the ESXi installer from your USB flash drive, then choose that same flash drive as the ESXi install target, it's all pretty darn simple and fast. All the other hard drive data remains untouched. VMware can actually install on any flash drive that's 1GB or greater in capacity, explained at the blogs.vmware.com here:

    1.  What size USB/SD should I use?

    The minimum disk size required to install ESXi is 1GB. When booting USB/SD there is little benefit to using a larger device because any space beyond the 1st GB will go unused.  When choosing a USB/SD boot device, it’s not the size of the device that is important but the reliability of the device.  Be sure to use good quality USB/SD devices.

    2.  How long will a USB/SD device last?

    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.

    Since the USB drive is mostly just read at boot time, the speed of the hypervisor is not held back at all, once the boot is done. You can even get Microsoft Hyper-V to install on a 8GB USB drive as well, read more at Microsoft TechNet. Probably makes most sense for the GUI-less variant of Hyper-V.

    So, why wouldn't you think of using USB drives for ESXi, especially now that many server motherboards having an on-the-motherboard USB socket these days? Well, one barrier was Windows folks getting scared off by VMware's Format a USB Flash Drive to Boot the ESXi Installation or Upgrade that required Linux, causing them to simply burn a CD or DVD of the install ISO. Then along came this little gem of a post from Kent Chen, on using Rufus, on July 2013, How To Format A USB Flash Drive to Boot VMware ESXi 5 Installation on Windows, along with RobWillis.info video.

    There are many methods I've used to create bootable media for ESXi, including the methods outlined below that each have some significant drawbacks and dangers.

    Over the years, having had to deal with this issue in my home lab quite often, and I'm quite glad to share this super fast fix for re-using USB flash drives (thumb drives, USB sticks, etc.), with these advantages:

    • simple GUI
    • can be run from an EXE that doesn't require any installation
    • doesn't require careful attention to command line partitioning commands that can be a bit dangerous
    • much faster than other methods
    • seems to work, every time, back on Windows XP, right through Windows 8

    Here's the 4 minute video outlining the actual 2 minute procedure to create the USB flash drive with the ESXi 5.5 installer.

    Download Rufus, straight from the author at rufus.akeo.ie, or from reboot.pro, then follow the step-by-step instructions below.

    double-click-to-launch-the-.exe-you-downloaded
    double-click to launch the .exe you downloaded
    User-Account-Control-say-Yes
    'User Account Control' say Yes
    Just-close-the-Update-policy-and-settings-dialogue-a-new-feature-in-Windows-8.1
    Just close the 'Update policy and settings' dialogue
    Rufus-update-policy-Do-you-want-to-allow-Rufus-to-check-for-application-updates-select-No
    'Rufus update policy' 'Do you want to allow Rufus to check for application updates' select No
    chose-your-ESXi-ISO-image-file
    choose your ESXi ISO image file
    Replace-menu.c32-say-Yes
    'Replace menu.c32' say Yes
    WARNING-ALL-DATA-ON-DEVICE-YOUR-DEVICENAME-WILL-BE-DESTROYED-click-OK
    ‘WARNING ALL DATA ON DEVICE [YOUR DEVICENAME] WILL BE DESTROYED’ click OK
    When-bottom-left-says-DONE-click-Close
    When bottom-left says 'DONE' click Close
    Remember-to-safely-eject-the-USB-device-when-youre-done-with-it
    Remember to safely eject the USB device when you're done with it. You do do that, don't you?

    See also

    Use ESXi-Customizer GUI to inject multiple driver VIBs into your ESXi installer ISO by Paul Braren Dec 16 2013, works great for ASMedia (SATA), Realtek (NIC), and LSI (RAID)

    Rufus let's you quickly and easily reformat an ESXi USB flash drive back to full capacity by Paul Braren Sep 10 2013, Windows command prompt, using diskpart and Linux Live USB Creator

    Create a bootable VMware ESXi 5 USB stick in Windows and perform a scripted installation by Ivo Beerens Sep 17 2011, back in the old days, Windows admins were more comfortable using manual cloning tools like Ghost

    ESXi3.5 Update 2 Build 110271 (Aug 13) install on USB key - here's an informal USB HCL, and a tip on later re-formatting for re-use of the USB key by pbraren Aug 23 2008


    Jul 04 2014 Update

    A lot of questions surrounding the use of USB keys for ESXi inevitably arise, remember, my focus is simplicity, in a home lab where support is likely non-existent. So logging isn't necessarily a priority.

    Read more at

    Installing ESXi 5.x on a supported USB flash drive or SD flash card (2004784)

    Creating a persistent scratch location for ESXi 4.x and 5.x (1033696)

    About the Scratch Partition


    Feb 27 2015 Update

    Of course, you may wonder, what USB flash drive do I buy? Well, I’m still working on testing this with vSphere 6, but so far, so good. Particularly with newer hardware that lets you set the BIOS to enable USB legacy mode support, just in case you encounter issues booting a USB 3.0 device.
    Nice little USB flash drive choice for that ESXi in your home lab

    SanDisk Ultra Fit™ CZ43 16GB USB 3.0 Low-Profile Flash Drive

    19qRq6m
    SanDisk Ultra Fit 16GB ASIN B00LLEN5FQ

    Mar 12 2015 Update

    With ESXi 6.0 now released, worth noting that Rufus still works just fine, including the new but very similar Rufus 2.0 Portable, and the USB flash drive pictured above.


    June 12 2015 Update

    Things have improved, for under $10 you can get the 16GB SanDisk Ultra Fit, and if using a USB 3.0 port, you can create the ESXi bootable media in well under a minute.

    See also