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[EX] While booting up, switch stuck in db> mode



Article ID: KB20635 KB Last Updated: 05 Mar 2017Version: 2.0

When the EX switch is stuck at the db> prompt, capturing information will help in understanding the reason why the EX switch crashed and help determine a root cause.


While booting up the EX switch, it is stuck at the db> prompt.  How do I recover?  What data should I collect if I need a Root Cause Analysis?

  1. First, collect the following command outputs from db> mode / prompt :

  2. db> x/s version     
    db> alltrace
    db> ps
    db> show allvms
    db> show msgbuf
    db> show registers
    db> show lock
    db> show uma

  3. After the information in step 1 is collected, enter "cont" to continue:
  4. db> cont

    Do you get the CLI prompt?

    • No - Continue with Step 3.
    • Yes - Jump to Step 4.

  5. Reboot, and try and recover from loader mode (loader>).  If you do NOT get a loader> prompt, open a case with your technical support representative.  A Format Install may be required.
    1. To recover the EX switch from the loader> prompt, reinstall the Junos software using one of the following methods:
    2. If a Root Cause Analysis is required after recovering, perform the steps in KB20569 - Collecting Logs from Juniper EX series Devices.

  6. At the CLI prompt, check to see if there are any core files on the switch with the command show system core-dumps. If there are core dumps please go to shell by typing "start shell" and then "cd" to the /var/core-dumps directory and FTP them to a server.

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