File Corruption from primary Junos Image and system booted from secondary Imange.

Today I got an alarm of OSPF state change in Juniper Ex3300 l3 switch 48ports. I woonder when I login into the box, I got a Warnig in Juniper


Warning:

****************************************************************************************
** **
** 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. **
** **
****************************************************************************************

Generally this thing occurs when we have some files in primary partition got corrupted during the switch switchover because of ungraceful power shutdown issue or sudden power loss.


I did following steps to resolve the issue:


Command1: request system snapshot media internal slice alternate --> For repairing the primary partition. No reboot is required for the command.


Command2: Check storage partiions status
show system storage partitions
Command 3: show system snapshot media internal


root> show system snapshot media internal
Information for snapshot on internal (/dev/da0s1a) (primary)
Creation date: Feb 24 11:32:07 2012
JUNOS version on snapshot:
jbase : 10.4I20120224_1123_bshekar
jcrypto-ex: 10.4I20120224_1123_bshekar
jdocs-ex: 10.4I20120224_1123_bshekar
jkernel-ex: 10.4I20120224_1123_bshekar
jroute-ex: 10.4I20120224_1123_bshekar
jswitch-ex: 10.4I20120224_1123_bshekar
jweb-ex: 10.4I20120224_1123_bshekar
jpfe-ex42x: 10.4I20120224_1123_bshekar
Information for snapshot on internal (/dev/da0s2a) (backup) <-- provides info for this slice/partition the switch booted off of and the date the file system was created
Creation date: Feb 14 05:42:42 2012    <-- if less than alarm date then customer should snapshot (it is a good way to confirm
JUNOS version on snapshot:
jbase : 11.2-20120214.0
jcrypto-ex: 11.2-20120214.0
jdocs-ex: 11.2-20120214.0
jkernel-ex: 11.2-20120214.0


Command 4. To get rid of the above alarm, use the following command to ensure that the switch boots from the primary partition:


request system reboot slice alternate media internal

Command 5:  following commands are issued to verify the Junos image installed on each slice:
                   user@switch>show system snapshot media internal slice 1
        user@switch>show system snapshot media internal slice 2


Lat Option: Junos Reconfiguration.