Booting A Juniper Switch From USB

I frequently see Juniper EX2200 and EX3300 switches with faulty flash. If you need to recover some data from one, or are just looking to play with a dead switch, you can boot it from USB.

You will need a USB key that was created as a recovery disk from a working system. It may also be possible to flash it with a computer and Junos packages.

Insert the USB key and power on the switch.

Press Enter when you see this prompt:

Press Enter to stop auto bootsequencing and to enter loader prompt.

Check that you see two disks with the "lsdev" command:

loader> lsdev
disk devices:
        disk0 - USB storage device 0
        disk1 - USB storage device 1
net devices:
        net0:

Run the "show" command and look for the line that says

loader> show
LINES=24
baudrate=9600
boot.btsq.disable=0
boot.current=upgrade
(omittedfor brevity)
loaddev=disk0:
(omitted for brevity)

Set this to disk1: then save and reboot

loader> set loaddev=disk1:
loader> save
Saving environment to flash... done
loader> reboot
Resetting...

If your USB key has an activity LED, you should see it flashing while it boots.