JunOS : Versions running on dual partitions are not same

By | April 13, 2018

Having the following notification on the console output after booting your Juniper EX switch?

WARNING: JUNOS versions running on dual partitions are not same

This might have been caused by an incomplete/failed upgrade of JunOS. Either way, unless this is the result of an action made on purpose, it is important that both slices have the same mirrored content.

To resolve this issue, make sure you are currently booted on the slice with the version you want to run into production. To find out, run the following command :

show system snapshot media internal

You will have an output similar to this :

> show system snapshot media internal
fpc0:
--------------------------------------------------------------------------
Information for snapshot on       internal (/dev/da0s1a) (backup)
Creation date: Jan 20 07:16:48 2016
JUNOS version on snapshot:
  jbase  : ex-12.3R12.4
WARNING: snapshot format is incompatible with the software currently running
Information for snapshot on       internal (/dev/da0s2a) (primary)
Creation date: Jan 1 00:05:11 2010
JUNOS version on snapshot:
  jdocs-ex: 15.1R6.7
  junos  : ex-15.1R6.7
  junos-ex-4200: 15.1R6.7
  jweb-ex: 15.1R6.7

As we can see, we are currently running on the secondary slice (/dev/da0s2a), running v15.1R6.7. The primary slice (/dev/da0s1a) is out of sync.

In that case, the healthy slice (/dev/da0s2a) and version we want to run into production is 15.1R6.7, we will replicate to the primary slice (/dev/da0s1a) using the builtin JunOS snapshot mechanism. In order to do that, we will use the following command :

request system snapshot slice alternate

NOTICE : This will format the slice marked as “backup” and copy the slice marked as “primary” to it.

This will take a little while, and system might become unstable under certain conditions. Here is the output following that command :

> request system snapshot slice alternate
System may go unstable if module traces or syslog mesages are enabled during snapshot.
It is recommended to disable all debug logging.
Do you wish to continue? [yes,no] (no) yes

fpc0:
--------------------------------------------------------------------------
Formatting alternate root (/dev/da0s1a)...

Copying '/dev/da0s2a' to '/dev/da0s1a' .. (this may take a few minutes)
The following filesystems were archived: /

This should take less than 10 minutes. Once done, validate once again both slices with this command :

show system snapshot media internal

Then it should look like :

> show system snapshot media internal
fpc0:
--------------------------------------------------------------------------
Information for snapshot on       internal (/dev/da0s1a) (backup)
Creation date: Apr 13 19:15:36 2018
JUNOS version on snapshot:
  jdocs-ex: 15.1R6.7
  junos  : ex-15.1R6.7
  junos-ex-4200: 15.1R6.7
  jweb-ex: 15.1R6.7
Information for snapshot on       internal (/dev/da0s2a) (primary)
Creation date: Jan 1 00:05:11 2010
JUNOS version on snapshot:
  jdocs-ex: 15.1R6.7
  junos  : ex-15.1R6.7
  junos-ex-4200: 15.1R6.7
  jweb-ex: 15.1R6.7