When QFX5100/EX4600 device does not work properly or does not boot normally, performing a Junos recovery may resolve the issue.
A recovery image is created automatically on the switches. If a previously-running switch is powered on and unable to boot using a Junos OS image, you can boot the switch using the recovery Junos OS image by selecting one of the saved images.
This procedure specifically applies to QFX5100/EX4600.
Select Junos Recovery using the UP and DOWN keys after hypervisor Reboot (request system reboot hypervisor) on CLI or force power cycle:
Available images will be shown. Select an option according to your request:
Double check for selection:
Formatting for Junos data and Junos config can be done separately:
For QFX10K and EX4300-MP, refer to KB33990 - Recovery installation for QFX10K and EX4300-MP. [juniper.net]