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Creating an Emergency Boot Device for Routing Engines with VM Host Support

If Junos OS on your device is damaged during loading in a way that prevents it from loading completely, you can use the emergency boot device to revive the device. The emergency boot device repartitions the primary disk and reloads a fresh installation of Junos OS. For Routing Engines that support VM host, you can use a USB storage device with at least 8 GB of free space to create an emergency boot device.

To create an emergency boot device on a device with VM host support :

  1. Copy the installation media into the device’s /var/tmp directory.
  2. Insert the USB storage device into the device’s USB port.
  3. In the UNIX shell, navigate to the /var/tmp directory:
  4. Log in as su:

    Super User (su) is one of the predefined login classes with preset permissions.

  5. Gunzip the copied file.

    For example, to convert junos-vmhost-install-usb-mx-x86-64-15.1F6.8.img.gz to junos-vmhost-install-usb-mx-x86-64-15.1F6.8.img, , use the following command: gunzip junos-vmhost-install-usb-mx-x86-64-15.1F6.8.img.gz

  6. Issue the following command:

    where:

    The following code example can be used to create an emergency boot device by using a USB storage device:

    Note:

    In the dd command, use junos-vmhost-install-usb-mx-86 for RE-MX-X6 and RE-MX-X8 Routing Engines and junos-vmhost-install-ptx-86 for RE-PTX-X8 Routing Engine respectively.

  7. Log out as su:

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