Juniper dual partitions

To show the current active and booted partitions:


my_ex4200> show system storage partitions
fpc0:
----------------------------------------------------------------------
Boot Media: internal (da0)
Active Partition: da0s2a                <--------- Active
Backup Partition: da0s1a
Currently booted from: backup (da0s1a)  <--------- Booted

Partitions information:
  Partition  Size   Mountpoint
  s1a        184M   /
  s2a        183M   altroot
  s3d        369M   /var/tmp
  s3e        123M   /var
  s4d        62M    /config
  s4e               unused (backup config)

fpc1:
----------------------------------------------------------------------
Boot Media: internal (da0)
Active Partition: da0s2a
Backup Partition: da0s1a
Currently booted from: backup (da0s1a)

Partitions information:
  Partition  Size   Mountpoint
  s1a        184M   /
  s2a        183M   altroot
  s3d        369M   /var/tmp
  s3e        123M   /var
  s4d        62M    /config
  s4e               unused (backup config)

To show the software versions installed on the respective partitions:


my_ex4200> show system snapshot media internal
Information for snapshot on internal (/dev/da0s1a) (backup)
Creation date: Feb 2 08:43:02 2012
JUNOS version on snapshot:
  jbase  : 10.4R9.2
  jcrypto-ex: 10.4R9.2
  jdocs-ex: 10.4R9.2
  jkernel-ex: 10.4R9.2
  jroute-ex: 10.4R9.2
  jswitch-ex: 10.4R9.2
  jweb-ex: 10.4R9.2
  jpfe-ex42x: 10.4R9.2
Information for snapshot on internal (/dev/da0s2a) (primary)
Creation date: Jan 5 16:25:17 2013
JUNOS version on snapshot:
  jbase  : ex-11.4R5.7
  jcrypto-ex: 11.4R5.7
  jdocs-ex: 11.4R5.7
  jkernel-ex: 11.4R5.7
  jroute-ex: 11.4R5.7
  jswitch-ex: 11.4R5.7
  jweb-ex: 11.4R5.7
  jpfe-ex42x: 11.4R5.7

To boot from the alternate partition (for a quick fail-back of software version):

my_ex4200# request system reboot slice alternate