I'll check the link shared.
One more quick question How much time does it typically take to migrate to Tableau server from 1 hardware to other ? so that Tableau server can be live again ?
I've never performed a migration like this for Tableau Server. It's going to largely depend on how many users and how much content you have.
You can (and should) perform a test migration as per the license conditions I linked to and you'll know for sure then.