Recovery Using an Emergency Boot Device (Junos OS)

If the device’s Junos OS software is damaged in some way that prevents Junos OS software 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 software.

Certain hardware platforms run an upgraded FreeBSD kernel (FreeBSD 10.x or later) instead of FreeBSD 6.1. To determine if your system uses Junos OS with upgraded FreeBSD, see: Junos kernel upgrade to FreeBSD 10+.

The procedures outlined in this section discuss how to create an emergency boot device for any ACX Series or MX Series router.

To create an emergency boot device:

If Junos OS on the device is damaged in some way that prevents the software from loading properly, you can use an emergency boot device to repartition the primary disk and load a fresh installation of Junos OS. Use the following procedure to create an emergency boot device.

To create an emergency boot device:

To reinstall Junos OS:

1. Connect to the device's console port (either directly or through a console server).

2. Insert the emergency boot device into the QFX Series switch.

3. Reboot or power cycle the device.

4. As soon as the device reboots, keep pressing Esc until the boot options menu opens.

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   Press Esc for boot options
   ...
   Intel(R) Xeon(R) CPU  @ 2.50GHz                                       2.50 GHz
   V0018.8                                                           16384 MB RAM
    Continue
    Boot Manager
    Device Manager
    Boot From File
    Setup Utility  

   Note:

   You might have to reboot or power cycle the device more than once if you miss hitting Esc to open the boot options menu.

5. In the boot options menu, select Boot Manager.

6. In the Boot Manager menu, select the emergency boot device. In this example, the emergency boot device is the USB device.

   Note:

   In later releases, the Boot Manager menu might display two different entries for the same USB recovery device. Select the EFI USB Device entry.

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   ┌──────────────────────────────────────────────────────────────────────────────┐
   │                                Boot Manager                                  │
   └──────────────────────────────────────────────────────────────────────────────┘
   Boot Option Menu          
   
    SSD0 : ATP M.2 2242                
    IBA GE Slot 0101 v1350             
    IBA GE Slot 0102 v1350             
    USB : General Udisk                
    SSD1 : ATP M.2 2242                
    IBA GE Slot 0103 v1350             
    EFI HDD Device (ATP M.2 2242)      
    Internal EFI Shell                 
   

   The Juniper Linux Installer or GNU GRUB menu opens. The menu and options may differ slightly depending on the platform and release.

7. If you have Junos OS software from the factory installed on the emergency boot device, the software prompts you with the following options:

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   Juniper Linux Installer - (c) Juniper Networks 2014
               Reboot                                                    
               Install Juniper Linux Platform                           
               Boot to host shell [debug]

   Select Install Juniper Linux Platform to install the Junos OS software from the emergency boot device.

   Note:

   Depending on the platform and release, you may see different entries such as Install Juniper Linux, Install Juniper Linux Platform, or Install Juniper Linux with secure boot support.

8. The device copies the software from the emergency boot device, occasionally displaying status messages. Copying the software can take up to 12 minutes.

9. After the software is copied to the device, the device reboots from the internal flash storage on which the software was just installed.

   Note:

   If the Boot Manager menu includes both SSD drive and EFI HDD Device entries, manually select the EFI HDD Device option.

   When the reboot is complete, the device displays the Junos OS login prompt:

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   root@switch#

10. Create a new configuration as you did when the device was shipped from the factory, or restore the previously saved configuration file to the device.

11. Remove the emergency boot device.

To reinstall Junos OS:

1. Insert the removable media emergency boot device into the device.

   Note:

   You can store a configuration on installation media such as a PC Card or USB stick.

2. Reboot the device.

   If the CLI is still active, issue the request system reboot command from command mode to reboot the device.

   If the CLI is not working, manually power off the device using the main power switch, wait 10 seconds, and then power the device back on.

3. When the software prompts you with the following question, type y:

   Note:

   Junos OS with upgraded FreeBSD does not display the following warning. To determine if your system uses Junos OS with upgraded FreeBSD, see: Junos kernel upgrade to FreeBSD 10+.

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   WARNING: The installation will erase the contents of your disk. Do you wish to continue (y/n)? y

   The device copies the software from the removable media emergency boot device onto your system, occasionally displaying status messages. Copying the software can take up to 45 minutes, depending on the device. When the process is complete, the system boots into Amnesiac state and the login prompt is displayed.

4. Remove the removable media emergency boot device.

   Note:

   For SRX300, SRX320, SRX340, SRX345, and SRX380 firewalls: When one of these firewalls is already booted with a recovery image, you cannot recover the firewall using a junos-install-media-usb* image from an already-inserted bootable USB device. If you unplug the bootable USB device and plug the device back in, then you can install the recovery image from the USB device. This behavior is designed to avoid the scenario where someone installs a recovery image and issues a reboot command for some other purpose, but the device copies and installs the second image from the USB device instead of using the original recovery image.

5. Log in as root on the device’s console port and issue the request system reboot command from command mode to reboot the device.

   The device reboots from the boot device on which the software was just installed. When the reboot is complete, the device displays the login prompt.

6. Create a new configuration as you did when the device was shipped from the factory, or restore a previously saved configuration file to the system. For more information, see Configuring Junos OS for the First Time on a Device with a Single Routing Engine, Configuring Junos OS for the First Time on a Device with Dual Routing Engines, and Restoring a Saved Configuration.