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Troubleshooting a Switch That Has Booted from the Backup Junos OS Image

Problem

The switch boots from the backup root file partition. This event is flagged in two ways:

  • Upon login through the console or management port, the following warning message is displayed:
    WARNING: THIS DEVICE HAS BOOTED FROM THE BACKUP JUNOS IMAGE      
                                                                       
    It is possible that the primary copy of JUNOS failed to boot up  
    properly, and so this device has booted from the backup copy.    
                                                                       
    Please re-install JUNOS to recover the primary copy in case      
    it has been corrupted.                                           
    
  • The following alarm message is generated:
    user@switch> show chassis alarms
    1 alarms currently active
    Alarm time               Class  Description
    2011-02-17 05:48:49 PST  Minor  Host 0 Boot from backup root
    

Solution

Install a new Junos OS image on the partition that had the corruption, or take a snapshot of the currently active partition and use it to replace the image in the backup partition:

user@switch# request system snapshot media internal slice alternate
 Copying '/dev/da0s2a' to '/dev/da0s1a' .. (this may take a few minutes)
The following filesystems were archived: /

Published: 2011-03-28