Disaster Recovery for Edge Appliances - alternate version

Versions 2.5 & 3.0

Applies to Platform: 4i Edge 112, 4i Edge 313, 4i Edge 515
Updated on: 27 July 2015

This lesson illustrates how to create and use the USB recovery stick for your Endian 4i Edge Appliance.

Disaster Recovery Key

Disaster Recovery Key is an easy to use and reliable solution for the automatic on the fly recovery of a broken system. Using Disaster Recovery Key you can restore your system to the point of the most recent backup.
Disaster Recovery Key always installs a specific version of the software and restores a backup if available, it can be used in case of a faulty system or if a system becomes unrecoverable after an upgrade.


  • Disaster Recovery Image (ZIP file, see next section).
  • USB stick drive.

Download the Disaster Recovery Image and create the Disaster Recovery USB stick drive

Get a clean USB stick, then log in to the Endian Network, go to the recovery keys download page and choose the appropriate image for your device.

Create a bootable USB stick following this lesson. Once done, you will see two partitions on the USB stick, described in the next section.

Filesystem Layout

rec_boot Partition

This partition is formatted using the VFAT filesystem, so that it can be accessed from all the most common operating systems, (Linux, OS X, Windows etc.). Indeed, this partition contains customizable settings, described in the remainder of this article, so it proves useful to allow access -and to modify files if necessary, from every workstation. In this directory, two files are important and described blelow.

The allow_boot file must be present, otherwise the recovery process will not start. Right after the recovery is finished, the allow_boot file will be renamed to allow_boot.disabled to avoid reboot loops.


To use again in the future the recovery key, rename allow_boot.disabled to allow_boot.

The wipe_userdata file, if present, will completely wipe out  the user data on the appliance. In embedded machines, where an SD card is used to store user data, this amounts to erase the entire SD card's content. The SD card directory layout will be recreated at the first boot.


All the user data content (both settings and logs) are removed, so make sure you have a backup somewhere if you intend to restore user's data later.

To avoid removing user's data, simply delete the wipe_userdata file or rename it to wipe_userdata.disabled: This will keep the current content of the SD card.

rec_root Partition

This partition contains the ext3 root filesystem of the live recovery key, along with the recovery program itself. It should not be modified.

Recovery process

The recovery procedure in itself is very easy. Plug the USB disaster recovery key in the appliance and turn it on.  If you have a 4i Edge 112, make sure you use the top usb plug only (see image below). The procedure is completely automatic and you do not need to interact. At the beginning of the installation, some beeps at regular interval indicate the beginning of the process. Once the process is finished successfully, you will hear again some beeps, this time with no regular interval between them.

The first boot after the recovery process has successfully completed may take up to 10-15 minutes.


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    Marco Morsiani

    how long does it takes the recovery procedure after plugging the key?