[Koha] Advice for OS upgrade - Koha is installed

Hi, I have installed Koha 3.12.00 on Ubuntu Server 12.04 by packages method, having 1000+ records. Now, I am planning for Ubuntu OS upgrade from 12.04 to 14.04. Even though, It is not a Koha related query, my intention is, existing Koha should not get damaged, therefore, I would like to know, regarding OS upgradation (Not Koha Upadation) 1) What are the precautions one should take, apart from taking MySQL DB backup ? 2) Does OS upgrade affect the existing Koha, Installed on System? 3) And any other related advice ..for OS Upgradation or best practices? since, I never did an OS upgrade, your feedback is really help me to proceed further! With Thanks Satish MV Govt. Engineering College, Hassan Karnataka, India. +91-9449765737 --