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Mount FreeNAS UFS-Harddrives

Sometimes it could be necessary to rescue data from a FreeNAS hardisk or other UFS-formatted drives. UFS will not be recognized and mounted on GNU/Linux or Windows automatically. To read data from these disks on GNU/Linux some steps are needed to be done. For Microsoft Windows® third party drivers are available for this purpose.

To connect a dismounted FreeNAS harddrive to a desktop or notebook computer a USB adapter could be used. There are several available on the market, e.g. from Digitus or trifoo.

Please note that a slightly damaged harddisk may still work if it is directly connected to a computer via S-ATA or IDE (P-ATA) but it may not work via USB adapter.

Mount UFS with GNU/Linux

This How-To describes how to mount a UFS-formatted harddisk under GNU/Linux which was formatted with UFS2 from FreeNAS 0.69.2.

You need to do the following steps:

  1. Open a console window
  2. In the console, type
    sudo modprobe ufs

    to load the UFS driver

  3. Connect the harddrive with the GNU/Linux-PC via USB
  4. Type
    dmesg | tail

    in the console window. In the output you will find the name of the device, e.g. sdb1.

  5. Create a mount point in your home directory
    mkdir ~/ufs
  6. Mount the connected harddisk
    sudo mount -t ufs -o ufstype=ufs2 /dev/sdb1 $HOME/ufs

    If this do not work your system may allow read access only. Try one of the following commands

    sudo mount -t ufs -ro ufstype=ufs2 /dev/sdb1 $HOME/ufs
    sudo mount -t ufs -o ufstype=ufs2,ro /dev/sdb1 $HOME/ufs
  7. If you used a rather old FreeNAS version you may succeed with “ufstype=44bsd“.
  8. The content of the FreeNAS USB-harddisk is now accessible in ~/ufs

Mount UFS with Windows

To mount UFS1 and UFS2 harddrives in Microsoft Windows® you can use:

  • UFS Explorer (Shareware) from SysDevSoftware (Windows XP or higher, GNU/Linux Debian 6 compatible or higher, Mac OS X 10.7 or higher)
  • ufs2tools (free of charge, proprietary license), (Windows 2000, XP, Vista, 7, 8)
  • NEW Linux Reader – Freeware from Diskinternals (read-only)

I have not tested one of these programs yet. So I can not say anything whether these programs are reliable or work as expected.


If you used RAID or filesystem encryption on the harddisk in question this how-to will not work unfortunately. But UFS-Explorer from SysDevSoftware should give access to RAID-harddrives with the Raid-Access-Plugin at least.

Picture Credits

CC0 - Public Domain (Pixabay)


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