You just loaded that new code on your WLC and something blew up! Quickly you scramble to start looking through the manual or start downloading and reapplying the previous level of code.
Did you know the controller saves the previous version of code on the controller and all you have to do is change the boot image to active? When you upgrade the WLC with a new image , the WLC automatically writes the new image as the primary image and the previously existing primary image is written over the backup image.
Note: The previously existing backup image will be lost !
Below are snips of a backup in progress
(Cisco Controller) >show boot
Primary Boot Image............................... 4.2.176.0 (active)
Backup Boot Image................................ 4.2.130.0
(Cisco Controller) config>boot ?
primary Sets the primary image as active.
backup Sets the backup image as active.
(Cisco Controller) config>boot backup
(Cisco Controller) >reset system
The system has unsaved changes.
Would you like to save them now? (y/N)
(Cisco Controller) >show boot
Primary Boot Image............................... 4.2.176.0
Backup Boot Image................................ 4.2.130.0 (active)