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Restoring Junos OS

 

To restore Junos OS on a PTX10008 or a PTX10016 router refer to the following sections:

Creating 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.

Before you begin, you need to download the installation media image for your device and Junos OS release from https://www.juniper.net/customers/support/ .

Note

You can create the emergency boot device on another Juniper Networks router or router, or any PC or laptop that supports Linux. The steps you take to create the emergency boot device vary, depending on the device.

To create an emergency boot device:

  1. Use FTP to copy the installation media image into the /var/tmp directory on the device.
  2. Insert a USB device into the USB port.
  3. From the Junos OS command-line interface (CLI), start the shell:
    user@device> start shell
    %
  4. Switch to the root account using the su command:
    % su
    Password: password
    Note

    The password is the root password for the device. If you logged in to the device as root, you do not need to perform this step.

  5. Do gunzip of the installed media file.
  6. Enter the following command on the device:
    root@device% dd if=/var/tmp/filename of=/dev/da1 bs=16k


    The device writes the installation media image to the USB device:

  7. Enter the following command:
    root@device% dd if=/var/tmp/filename of=/dev/da0 bs=1048576


    The device writes the installation media image to the USB device:

    Note

    The device automatically create a recovery Junos OS image.

    The “Select a recovery image” menu appears on the console when one of these routers is booted and unable to load a version of Junos OS. You can follow the instructions in the “Select a recovery image” menu to load the Junos OS image for one of these routers.

  8. Log out of the shell:
    root@device% exit
    % exit
    user@device>

Performing a Recovery Installation Using an Emergency Boot Device

If Junos OS on your device is damaged in some way that prevents the software from loading correctly, you may need to perform a recovery installation using an emergency boot device (for example, a USB flash drive) to restore the default factory installation. Once you have recovered the software, you need to restore the device configuration. You can either create a new configuration as you did when the device was shipped from the factory, or if you saved the previous configuration, you can simply restore that file to the device.

If at all possible, you should try to perform the following steps before you perform the recovery installation:

  1. Ensure that you have an emergency boot device to use during the installation. See Creating an Emergency Boot Device for QFX Series Switches for information on how to create an emergency boot device.

  2. Copy the existing configuration in the file /config/juniper.conf.gz from the device to a remote system, such as a server, or to an emergency boot device. For extra safety, you can also copy the backup configurations (the files named /config/juniper.conf.n, where n is a number from 0 through 9) to a remote system or to an emergency boot device.

    You can use the system snapshot feature to complete this step. The system snapshot feature takes a “snapshot” of the files currently used to run the PTX10000 Series router—the complete contents of the /config and /var directories, which include the running Juniper Networks Junos OS, the active configuration, and the rescue configuration—and copies all of these files into a memory source. See Creating a Snapshot and Using It to Boot a QFX Series Switch.

    Note

    System snapshot is not supported on the PTX10000 routers.

    Warning

    The recovery installation process completely overwrites the entire contents of the internal flash storage.

  3. Copy any other stored files to a remote system as desired.

To reinstall Junos OS:

  1. Insert the emergency boot device into the device.

  2. Power cycle the device.

    The emergency boot device is detected. At this time, you can load the Junos OS from the emergency boot device onto the internal flash storage.

  3. The software prompts you with the following option if you have a snapshot saved on the emergency boot device:

    Select Install Junos Snapshot install the snapshot.

    The software prompts you with the following option if you have Junos OS software from the factory installed on the emergency boot device.

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

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

    When the software is finished being copied from the emergency device to the device, the device reboots from the internal flash storage on which the software was just installed. When the reboot is complete, the device displays the Junos OS login prompt:

  5. 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.

  6. Remove the emergency boot device.

Related Documentation