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

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Article ID: KB20635 KB Last Updated: 17 Feb 2020Version: 3.0
Summary:

When an EX switch is stuck at db> prompt, capturing information will help in understanding the reason the EX switch crashed and help determine a root cause. This article explains how information can be captured for troubleshooting purposes.

 

Symptoms:

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

 

Solution:

Perform the following steps:

  1. First, collect the following command outputs from db> mode / prompt:
db> x/s version     
db> alltrace
db> ps
db> show allvms
db> show msgbuf
db> show registers
db> show lock
db> show uma
  1. After the information in step 1 is collected, enter cont to continue:

db> cont

Do you get the CLI prompt?

  • No - Continue with Step 3.

  • Yes - Jump to Step 4.
  1. 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 by using one of the following methods:
  1. If a Root Cause Analysis is required after recovering, perform the steps in KB20569 - Collecting Logs from EX series devices using the 'file archive' command.
  1. 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, go to shell by typing start shell, then cd to the /var/core-dumps directory, and then FTP them to a server.

 

Modification History:

2020-02-17: Article reviewed for accuracy; no changes required.

 

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