Troubleshooting a Switch That Has Booted from the Backup Junos OS Image
Problem
Description
The switch boots from the backup root file partition. It is possible that the primary copy of Junos OS failed to boot properly, which could indicate that it is corrupted. 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
If the switch is in a Virtual Chassis, the switch member number appears in the
Descriptionfield, where the switch is called a host.
Solution
Install a new Junos OS image on the partition that had the corruption, or take a snapshot (use request system snapshot) of the currently active partition and use it to replace the image in the alternate partition:
If the switch is a standalone switch or a Virtual Chassis primary switch, enter this command:
user@switch> request system snapshot slice alternate
If the switch is a Virtual Chassis member switch (not the primary), enter this command on the Virtual Chassis:
user@switch> request system snapshot slice alternate member member-id
where member-id is the Virtual Chassis member ID number.