Creating an Emergency Boot Device for a QFX Series Device

If Junos OS on your QFX Series 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 http://www.juniper.net/customers/support/ .

Note: The following procedure assumes that you are creating the device on a QFX3500 switch. You can create the emergency boot device on another Juniper Networks switch 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.

1. Use FTP to copy the installation media image into the /var/tmp directory on the switch.
2. Insert a USB device into the USB port.
3. From the Junos OS command-line interface (CLI), start the shell:
   user@switch> start shell

   %
4. Switch to the root account using the su command:
   % su

   Password: password

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

5. Enter the following command:
   root@switch% dd if=/var/tmp/filename of=/dev/da1 bs=16k

   
   

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

   root@switch% dd if=/var/tmp/install-media-qfx3500.junos_11.1 of=/dev/da1 bs=16k
   11006+1 records in
   11006+1 records out
   180332544 bytes transferred in 71.764266 secs (2512846 bytes/sec)
   

6. Log out of the shell:
   root@switch% exit

   % exit

   user@switch>