VC upgrade process for MX devices
+Deactivate GRES, NSR and commit sync
#deactivate chassis redundancy graceful-switchover
#deactivate routing-options nonstop-routing
#deactivate system commit synchronize
+ Installing the Junos OS software package on each Routing Engine in an MX Series Virtual Chassis prepares the Routing Engines to run the new software release after a reboot. This action is also referred to as arming the Routing Engines.
To install the Junos OS software package on all four Routing Engines from the primary router (member0-re0) in the Virtual Chassis
OR
If Image is added in Master Router Primary RE, then image will get added in all 4 RE’s of both RE’s.
Ø request system software add package-name
+Reboot using below command in Master Router Primary RE
Ø request system reboot all-members both-routing-engines
+Activate GRES, NSR and commit sync.
#activate chassis redundancy graceful-switchover
#activate routing-options nonstop-routing
#activate system commit synchronize