Junos Running on Backup Image // Denis Nolan

I’ve come across this mostly with SRX units where the device is running on a backup image. This generally happens if the unit suffers a power cut.

Message

***********************************************************************
**                                                                   **
**  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 and if auto-snapshot feature is not        **
**  enabled.                                                         **
**                                                                   **
***********************************************************************

Steps

show system alarms

1 alarms currently active
Alarm time               Class  Description
2022-03-07 09:05:08 GMT  Minor  Host 0 Boot from backup root

show chassis alarms

1 alarms currently active
Alarm time               Class  Description
2022-03-07 09:05:08 GMT  Minor  Host 0 Boot from backup root

show system storage partitions

Boot Media: internal (da0)
Active Partition: da0s1a
Backup Partition: da0s2a
Currently booted from: backup (da0s2a)

Partitions information:
  Partition  Size   Mountpoint
  s1a        2.4G   altroot
  s2a        2.4G   /
  s3e        185M   /config
  s3f        2.1G   /var
  s4a        224M   recovery
  s4e        15M

Note above stating Currently booted from: backup (da0s2a). This is the backup partition the unit has currently booted from. We’ll need to rectify this.

show system snapshot media internal

 show system snapshot media internal
Information for snapshot on       internal (/dev/da0s1a) (primary)
Creation date: Mar 7 09:05:02 2022
JUNOS version on snapshot:
  junos  : 15.1X49-D70.3-domestic
Information for snapshot on       internal (/dev/da0s2a) (backup)
Creation date: Mar 7 09:01:56 2022
JUNOS version on snapshot:
  junos  : 15.1X49-D70.3-domestic

request system snapshot slice alternate

This step may take a few moments to complete as advised:

dnolan@xxxxx-srx> request system snapshot slice alternate
Formatting alternate root (/dev/da0s1a)...
Copying '/dev/da0s2a' to '/dev/da0s1a' .. (this may take a few minutes)
The following filesystems were archived: /

request system reboot

request system reboot
Reboot the system ? [yes,no] (no) yes

Shutdown NOW!
[pid 76674]

dnolan@xxxxx-srx>>
*** FINAL System shutdown message from remote@xxxxx-srx> ***

System going down IMMEDIATELY

Unit should come live again on primary image after some time. Once live again check the system is correctly on primary partition.

show system storage partitions

Boot Media: internal (da0)
Active Partition: da0s1a
Backup Partition: da0s2a
Currently booted from: active (da0s1a)

Partitions information:
  Partition  Size   Mountpoint
  s1a        2.4G   /
  s2a        2.4G   altroot
  s3e        185M   /config
  s3f        2.1G   /var
  s4a        224M   recovery
  s4e        15M

Finally check alarms have cleared:

dnolan@xxxxx-srx> show system alarms
No alarms currently active

dnolan@xxxxx-srx> show chassis alarms
No alarms currently active

All done.