Installing the FreeNAS Image Directly to a USB Drive

The quickest and easiest way to get a FreeNAS server running is to write the image directly to a USB drive.  After imaging the drive you can plug it into the computer, set the bios to boot from the drive, and watch FreeNAS boot directly from USB.

I like to run FreeNAS directly from USB because it saves me from wasting a hard drive bay just for the operating system.  FreeNAS must have it’s own dedicated drive, it cannot reside on drives that will be part of a storage volume in the NAS.

This method requires no ISOs or blank CDs, all you need is a copy of the FreeNAS image and a USB flash drive that is 2GB or larger.  The advertised capacity of a thumbdrive isn’t always equal to its actual capacity.  My spare 2GB drive wouldn’t hold the image so I used a 4GB drive instead.  FreeNAS uses dual 1GB partitions so a true 2GB USB drive will hold the image just fine.  This problem usually only affects cheaper drives from shady manufactures, as long as you have a drive from a reputable manufacture you shouldn’t run into this issue.

1.  Download the compressed FreeNAS image file.

Instead of download the ISO file you need to download the IMG file instead.  Select the version, and architecture you intend to install from the download page then download the img.xz file.

Download the img.xz file.

2.  Extract the image file from the archive.

Before the image file can be loaded on a USB drive it must be decompressed to your hard drive.  I recommend using 7-Zip to extract the file, it’s free and works well.  The compressed file is only about 125MB in size but uncompressed it jumps up to 2GB so make sure to extract it to a location with enough space.

7-Zip works well for extracting compressed files.

3,  Write the Image to a USB Drive.

To write the image to a thumbdrive you’ll need a program called Win32DiskImager.  This program will transfer the raw disk image onto the USB drive.  To use the program download the zip file and extract the contents to a folder on your computer.  Then execute the program by running win32diskimager.exe.  Load the img file you’ve extracted by clicking on the folder icon and navigating to the location of the file.  Then select the drive letter of the USB drive in from the device dropdown box.

Be absolutely certain that you’ve selected the correct drive letter , you can easily corrupt a local drive if you’re not careful.   If the USB drive you’re using doesn’t have a fast write speed then expect the process to take a few minutes to complete.

Win32DiskImager can be used to write the raw image to a USB device.

4.  Boot from the USB drive.

Once the image has been transferred the device is ready to boot from.  Plug the drive into the machine that’s going to run FreeNAS and make sure the BIOS is configured to boot from it.  You should see the FreeNAS boot screen shortly after the computer starts booting from the USB drive.

General Thoughts on USB Installations

I try to install everything I can using USB drives, it’s been quite a while since I’ve actually had to burn a CD.  I’ll probably be able to remove the optical drive from my computer in the near future.  The process described in this post can be used for installing pfSense from USB.

For general testing and troubleshooting purposes I like to keep a copy of Backtrack installed on a USB drive.

Have you installed any other operating systems from USB?  Leave a comment below to share your tips for USB installations.


Sam Kear

Sam graduated from the University of Missouri - Kansas City with a bachelors degree in Information Technology. Currently he works as a network analyst for an algorithmic trading firm. Sam enjoys the challenge of troubleshooting complex problems and is constantly experimenting with new technologies.

23 thoughts on “Installing the FreeNAS Image Directly to a USB Drive

    1. Hey Ari,

      No, it doesn’t matter if the USB drive has been formatted or not. When you write the image to the flash drive it will apply the necessary file structure automatically. This process completely erases the contents of the USB drive so make sure to remove any important files first.

  1. Well I always install windows 7 from USB and sometimes run ubuntu desktop (liveCD) from USB, really handy compared to optical devices and faster. 🙂
    Removed my optical bay a long time ago, I don´t miss it at all.

    And thanks for the guide Sam!

  2. Your method really worked like a charm. I was thinking to boot from the iso and install it another USB Stick, but no need even for that. The stick prepared using above method boots the system directly. Thanks for posting this.

  3. Hi Sam, thanks for your info, I followed your advice and booted into Freenas perfectly. My only question is what is the long term reliability like having the freenas booting from a USB?. I.e will a usb in general have a shorter life than just say a traditional HDD.

    Though having said that I have had 3 HDD’s die on me in the last 6 months so I guess it doesn’t really matter haha.

    Thanks again for a great post.

  4. Hi Sam, thanks for putting together this How-To. I’m about to build my first FreeNas box. Can I use any USB 2.0 thumb drive or does it have to be a certain speed? I have an older Sandisk Cruzer 8GB USB 2.0 thumb drive I had laying around I’d like to use. Will this work?

    1. Pretty much any USB thumb drive will work, the speed really isn’t important. Once the system boots FreeNAS will run from RAM and not the USB stick. Having a faster USB drive will make it boot faster but won’t affect performance once it’s running.

  5. Hi,

    Is there a more current version of this? Would like to try it out but not if it’s four years old.

    Thanks for posting this. Seems simple enough.



      1. Hi Sam,

        Thank you for your tutorial. However I am a bit confused as to how to apply this method to Freenas 9.10.
        Using the link to the most recent version, only the ISO file is available not the image as you indicated in your step by step.

        Could you clarify when you say that “The same procedure does still work” when the img file is not a download option?

        Thank you

  6. Hi Sam,
    When you save FreeNAS configurations does it sort of write those config changes to the USB drive? How does it store my personal configuration changes?

        1. They are essentially the same although IMG files can be either compressed / uncompressed. You can still use Win32 Disk Imager to write the ISO file. Just change the file type to *.* when browsing for the ISO file. You could also change the file extension to IMG.

          I just tested and confirmed this process worked with the latest FreeNAS ISO file. I’m not sure why they changed formats. I’ll update the post to reflect this.

  7. Hi Sam,

    I have an HP Proliant Server which was running FreeNas from an USB drive.
    Today, after a power down, the FreeNas is not restarting, and I’m afraid the USB drive is damaged.
    I’d like to replace it with a new one, following your suggestions.
    Is there any risk that I lose the content of the hard disks by running a new version of FreeNas?
    Am I going to lose the settings that I had in the previous system?

    Thank you in advance for your help.

    1. I believe all of the configuration settings are stored on the USB drive and would probably be lost unless you can somehow recover the data or have a config backup. I don’t think there is any issue with recovering the data but to be honest I’m not sure what the correct procedure is in this case. I would advise reaching out on IRC or the FreeNAS forums for specific help in this instance since data recovery is involved.

  8. Good article. How come the official documentation doesn’t mention ANYTHING about this method? This seems much more straightforward than a full installation from .iso procedure…

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