How to prepare an Emergency USB Boot Disk with install-media file for high-end SRX

The procedures outlined in this section discuss how to create an emergency USB boot disk for SRX 3K and 5K Series with the help of a install-media file.

This applies to the following Junos platforms:

  • SRX1400
  • SRX3400
  • SRX3600
  • SRX5400
  • SRX5600
  • SRX5800

If the router’s Junos Software is damaged hence preventing the Junos Software from loading completely, you can use the emergency USB boot disk to revive the router. The emergency boot disk repartitions the primary disk and reloads a fresh installation of the Junos Software. The Junos software is kept as a backup in USB so that if there is any damage to the installed software it can be revived from the USB drive itself.

Perform the following procedure to prepare a USB Boot disk with install-media file:

1. Download install media file from the Juniper support website.

2. Login into a working firewall using root username and password.

3. Create the directory

4. Use FTP to copy the installation media into the firewall’s


5. Run this command from shell prompt:

(Make sure that the USB is on slot0 of routing engine)

6. Run this command from shell prompt:

Once it completes, unplug the USB and plug into a another firewall (slot0 of routing engine) in which compact flash is corrupted and then reboot the device.

Then you will observe a message that the device is booting from USB

Press Y to format the compact-flash and reinstall the Junos packages on it.

Once the installation is complete, the device will reboot automatically and prompt for ejecting the USB so that it can boot from the Compact-flash as shown below.

Once the device will reboot completely it will ask for user name, and it will allow you to go inside CLI> of the device.

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