Hi pavanae,
follow the docs http://docs.splunk.com/Documentation/Splunk/6.3.0/Installation/Upgradeto6.3onUNIX it also covers what you should backup. BTW, you should always store a backup outside of the system/server the backup was made .... but this is not Splunk related, this is common sense 😉
Also, it depends on the upgrading approach you choose if you require sudo or not: if you use the tar ball to upgrade, this is done as Splunk user. If you choose the rpm or dkg package, this is normally done by using sudo
Hope this helps ...
cheers, MuS
... View more