In this video I am going to show you how to take complete backup of your device using recovery mode before installing any new ROM or updating your device. Taking backup is good for safer side. If your update fails then you can atleast restore to previous version back again.
I am using philz touch recovery on my device. My device is xiaomi note 4G(rooted).
Preserve this backup on your PC/laptop or over the cloud. So that if required you can restore it.